Next extension target - no doubt; but not yet.
I love how JS has emerged from Tommy John surgery and being lost among pitching prospects (with D Underwood, J Stinnett, O de la Cruz, T Hatch, R Zastrynzy, etc.) to a guy that could be our #1 real soon. A contract like that would work out great for the Cubs if JS kept getting better and better. But like you said, they've got some time to see if he looks the part, and there are several areas of caution:
1) JS still hasn't completed a full MLB season. His 119 IP last season was by far the most of his career (and most since his previous career high of 98 in '17 at Myrtle Beach), and it's still not clear why he had to be shut down before Labor Day. If he can go 150+ IP this season (and still look good in the postseason
), I'm sure the Cubs front office will be thinking about this seriously.
2) The Cubs are already among the top teams in MLB with future $ committed. MLB.com showed that after the Happ deal, the Cubs are already 5th in MLB in payroll commitment for 2026, with the top 4 already being expected present-day contenders (Yankees, Padres, Braves, Mets). Obviously, only time will tell if this is a good or bad thing,
3) I believe the last player the Cubs "locked up" this early in the contract process was D Bote....
I'm thinking that, if things go as planned for the Cubs, they'll be looking to extend JS like they did NH, after his ARB1 year. If he has a super solid '23 season, he might make $2.5-3M in '24. He'd have to win the Cy Young for the Cubs to be looking at ARB2-4 being potentially more expensive than the contract you described.
So, I think that if the Cubs want him long term, they'll get him, and for a fair price.