Edited Apr. 5, 2020 at 10:51 p.m.
It's going to be really tough to find a team willing to give up a 1C. I'd guess Larkin is untouchable, Detroit should build around a young, talented center, not trade him away. Even if they draft a high-end center this year, you win cups by being deep down the middle and having a hot goaltender.
To answer your question in your description, there's several options out there:
1. Max Domi, who I'm not a huge fan of acquiring since he's really only had one good year. He's a good player, but can he consistently produce 70 point seasons and be a great-to-star player? I'm not sure I'm convinced...
2. Maybe Cirelli? I think Tampa will do absolutely everything they can to retain him, but it's going to be tough with the contracts they have.
3. Another long shot, but Dubas was interested in Dumba at the deadline and there have been talks between Toronto and MN revolving around Nylander and Dumba stemming back to when Nyalnder needed a contract. Could be an option worth exploring if Guerin believes he's a center, although Nylander is a stud and it would likely take more than Dumba to get him.
4. Signing Haula. Not my favorite option and his leg injuries concern me, but he's a speedy center and proved he can produce with Vegas.
5. Maybe the biggest long shot, trying to trade for Necas. It would cost a king's ransom, and more, but Necas would be an incredible addition.
6. Trading for a young prospect that's almost NHL ready, like Morgan Frost or Peyton Krebs. More risky, but could pay dividends if it worked out.
7. Maybe Chicago wants to move Dach to the middle where he belongs and would explore moving Strome. Like Domi, Strome also worries me but he just turned 23 so there's still time for him (Kevin Fiala just turned 23 and finally showed signs of being a star) and he flashed some skill. If we could get him for a decent price I'd like him as a medium risk and potentially high reward option.
8. Re-signing Galchenyuk. Probably a last resort here, but it's an option. Galchenyuk played pretty well his last 5 or so games at center so if he's willing to sign cheap and we aren't able to trade for a center, I could definitely see it happening.
9. Signing Kaprizov's CSKA teammate, Mikhail Grigorenko. He mainly played wing in the KHL but I suppose it's an option if Guerin thinks he's a center.
10. A long term option would be trading up in the draft if guys like Rossi or Stutzle fall outside the top 5. That idea sounds crazy to me, but I never though in a million years Zadina would fall to 6 in his draft year (he was pretty clearly the consensus 3rd best player prior to the draft) and I never would have thought a guy like Seider would have jumped to 6th overall last year, so while it's unlikely Rossi or Stutzle falls, it's absolutely a possibility. It takes two to tango of course, but moving up 5-6 spots in the draft isn't totally outlandish IMO. Teams like NJD, LA, MTL, even BUF are pretty set on young center talent. MTL might be unlikely since the draft is in Montreal and they'll want a shiny touted prospect to show off to their fans. But if I'm Guerin, I'm keeping in constant contact with those teams if it's pick 4/5 and Stutzle and Rossi are still available.
There's other options, but those are some ideas. I'd bet Domi or Galchenyuk are the most likely scenarios, but once again I'd be very cautious about trading for Domi. This got a little long but hopefully it gives you some food for thought.