Justin Verlander was drafted in 2004. Stephen Strasburg and Mike Trout were drafted in 2009 and Matt Chapman was drafted in 2014. It seems that on average an all-star player is drafted every 5 years. Of course there are players that fall in between the five year average. Bryce Harper was drafted in 2010. Mookie Betts was drafted in 2011 along with Javier Baez, Francisco Lindor Gerrit Cole and Trevor Bauer (loaded draft). The point I am making is I believe that the next generational talent could be already be in the MLB. After doing some research here are the candidates. If I am missing someone or if you disagree, please let me know in the comments.
Wander Franco (Tampa Bay Rays, SS) - Superstar hit tool with power.
Spencer Torkelson (Detroit Tigers, 1B/DH) - Future slugger.
Bobby Witt Jr (Kansas City Royals, SS) - Good hit tool with power and will be elite on defense.
Julio Rodriguez (Seattle Mariners, RF) - Crazy tools and young.
Jasson Dominguez (New York Yankees, OF) - The Martian. Enough said.
Dark Horse Candidates
Zac Veen (Colorado Rockies, CF) - Slugger that is not all swing and miss.
Jarred Kelenic (Seattle Mariners, CF) - Polished prospect with tools.
Ed Howard (Chicago Cubs, SS) - Expected to hit for power but everything else is there.
Adley Rutschman (Baltimore Orioles, C) - Gifted prospect.
Quinn Priester (Pittsburgh Pirates, P) - Incredible arm talent.
Hunter Greene (Cincinnati Reds, P) - Tommy John slowed him down but he can hit 100 with ease.
Long Shot Candidates
Jordyn Adams (Los Angeles Angels, CF) - Tons of tools but can he develop them. I think he can.
Ivan Herrera (St. Louis Cardinals, C) - Ivan can hit for power and the defense is superb.
Garrett Mitchell (Milwaukee Brewers, CF) - If the Brewers can change his swing he could be Christian Yelich 2.0.