The next possible major contract extension could be for Kyle Tucker. After Vladimir Guerrero Jr.'s mammoth $500 million deal, the focus shifts to the pending free-agent outfielder. He hits unrestricted free agency at the end of the season.
In the meantime, there has been very little traction on an extension. The latest reports suggest that nothing will happen for some time, but that reporting has one MLB insider irked.

The idea that the Chicago Cubs are going to wait to start offering Tucker contract extensions after trading for him got ripped by Mike Rodriguez, a team insider:
"Here we go, the same thing that happened with Vladimir Guerrero Jr., saying last Friday that Toronto and Vladimir were very close to closing a $500M extension. The next day, Saturday, they asked Vladimir and he said that it was a lie. The next day, Sunday, Passan published it. The same story."
Initial reports said the Toronto Blue Jays hadn't come close with Vladimir Guerrero Jr. On the next day, Guerrero Jr. himself said that was a lie, and then the next day he was signed.
Whether or not that's how the Tucker extension goes, Rodriguez can certainly see the pattern. He believes the team is working to get an extension done and that they're sending up smokescreens in the meantime just like what happened with Guerrero Jr. and the Jays.
Kyle Tucker not focusing on extension talks with Cubs
Kyle Tucker, if he hits free agency, is expected to have a number of suitors including the New York Yankees, Chicago Cubs and New York Mets. Ahead of that, the outfielder isn't worrying about a deal.

He said, via Sporting News:
"I haven’t thought about it that much. I’m just trying to come out here and play and put up wins and get my numbers. I’m just here to play baseball. I just let the other stuff kind of fall where it is and see what happens."
Tucker is off to a great start in his Cubs tenure. He's hitting .322 with 0.9 bWAR already. He has five home runs, 16 RBIs and three steals in the early going as the Cubs have started 9-6 and lead the NL Central over the Milwaukee Brewers.