Grant Cohn: 49ers' promising future will stall without more talent on roster

Jimmy Garoppolo is in the zone and the 49ers have won three in a row. They're one of the hottest teams in the league.

Just how bright is their future?

How many franchise cornerstone players do the 49ers really have?

I'm not talking Pro Bowl alternates or guys who used to be Pro Bowl talents or may become Pro Bowlers someday. I'm talking legitimate Pro Bowl players. Guys you can build a playoff team around right now.

Let's break down the 49ers roster and separate the former cornerstones from the potential cornerstones and the real cornerstones.

Group 1: Players formerly considered potential franchise cornerstones who are now expendable.

1. DB Jimmie Ward. First-round pick in 2014. Drafted to play nickel back. Got hurt and didn't play well. Moved to cornerback in 2016. Got hurt and didn't play. Moved to free safety this season. Flourished. Just kidding. Got hurt and didn't play well. A fragile athlete without a position who may not even start next season.

2. RB Carlos Hyde. Second-round pick in 2014. Drafted to replace Frank Gore. Never has rushed for 1,000 yards in a season. Will be a free agent during the offseason and probably won't sign with the 49ers.

3. DE Arik Armstead. First-round pick in 2015. Drafted to replace Justin Smith. Has missed 18 games, been on IR twice and recorded only six sacks in three seasons. May not be a starter in 2018.

4. DE Aaron Lynch. Fifth-round pick in 2014. Recorded 12.5 sacks his first two seasons in the NFL. Seemed like a replacement for Aldon Smith. But has gained weight, missed 18 games and recorded only 2.5 sacks the past two seasons. May be out of the league in a year or two.

Group 2: Players formerly considered franchise cornerstones who are getting old or declining.

1. LT Joe Staley. Five-time Pro Bowler. Hasn't made a Pro Bowl since 2015, but is a Pro Bowl alternate this season. Turned 33 in August. Seemed slower than usual this season. The 49ers need to find an heir apparent soon.

2. WR Pierre Garcon. Never been a Pro Bowler, but led the NFL in receptions with 113 in 2013. Turned 31 in August. Broke a vertebrae in his neck and is on IR. The 49ers probably will draft a receiver this offseason who can replace Garcon in a couple OF years.

3. DE Elvis Dumervil. Five-time Pro Bowler. Hasn't made the Pro Bowl since 2015. Tore his Achilles tendon in 2016. Has recorded only 5.5 sacks this season. Turns 34 on Jan. 19. A placeholder until the 49ers find a younger, better edge rusher.

4. S/LB Eric Reid. Made the Pro Bowl as a rookie free safety in 2013. Suffered three concussions and hasn't made the Pro Bowl since his rookie year. Moved to strong safety this season. Lost his job to Jaquiski Tartt and had to move to linebacker. Moved back to strong safety after Tartt got hurt. Probably will sign with another team this offseason.

Group 3: Players who have slim hopes to become franchise cornerstones.

1. OT Trent Brown. A Pro Bowl alternate this season. Arguably one of the best right tackles in the NFL. Must prove he can stay healthy and slim before he is considered elite. Played only 10 games this season, and weighs at least 355 pounds.

Group 4: Players who have moderate hopes to become franchise cornerstones.

1. WR Marquise Goodwin. Averaging 91.3 receiving yards per game the past six weeks. Playing like one of the best receivers in the NFL right now. Only 27-years old. Needs to play well for more than six games before we consider him a franchise cornerstone. A contender.

2. DE Solomon Thomas. The third pick in the draft this season. Plays hard, but has recorded only two sacks in 12 games. Missed OTAs and minicamp because he was in school. May improve in 2018 after he goes through an entire offseason workout program with the 49ers.

3. TE George Kittle. The second-leading receiver among rookie tight ends in the league this season. Has caught 36 passes for 373 yards and one touchdown in 13 games despite playing through hamstring, hip and ankle injuries. Has an opportunity to become the 49ers' starting tight end and go-to red-zone target for a long time.

Group 5: Players with high hopes to become franchise cornerstones.

1. LB Reuben Foster. Plays like a Pro Bowler, but gets hurt almost every game. Seems particularly susceptible to shoulder injuries. Left Sunday's game against the Tennessee Titans twice with stingers, hurt his shoulder during training camp and had rotator-cuff surgery during the offseason. Could become a franchise cornerstone if he doesn't keep missing games. Has missed six games already this season.

Group 6: Players who have high-in-the-sky-apple-pie hopes to become franchise cornerstones.

1. QB Jimmy Garoppolo. Extremely promising and wildly intriguing. Never has lost a game in the NFL as a starting quarterback. But has started only five games. And five games isn't a big enough body of work to declare anyone a franchise cornerstone, no matter how much optimism and hope that player generates for the future. Let's see what happens the rest of the season, and if the 49ers sign Garoppolo long term. Can't be a franchise cornerstone without committing to the franchise.

Group 7: Legitimate franchise cornerstones.

1. DE DeForest Buckner. One of the two or three best defensive tackles in the NFL right now even if numbers don't show it. Has recorded only three sacks this season and did not make the Pro Bowl, but should have. Ranks near the top of the league in hits on the quarterback, and will rank near the top in sacks once he gets a supporting cast and opposing teams can't double-team and triple-team him every play.

2. FB Kyle Juszczyk. The best fullback in the NFL and the only 49er who made the Pro Bowl. Will be a fixture on the 49ers offense for at least the next three years.

3. K Robbie Gould. The best kicker in the NFL and a Pro Bowl snub. Has missed only three kicks all season — two field goals and one extra point. Has been perfect since Week 8. Turned 35 on Dec. 6. Could be the 49ers kicker the next 10 years. Good kickers last.

So the 49ers have franchise cornerstones. But not nearly enough.

The search continues.