Right now, I am not sure Thomas is the best WR on his team never mind if there will be better players in the draft. Last year, there were only a small handful of WRs better than him. Again, which guy is he? He is probably closer to the guy last year, but you have to figure out why he is so inconsistent this year and dropping balls and whether it can be corrected at least with the team acquiring him.
I am also not sure Buffalo will give up a first rounder for him. It seems like every year they are linked to making massive trades and then end up making lesser trades. They were linked to making big trades for WRs last year and went a more valued route by getting Amari Cooper for a third and pick swaps. It has been a long time since they did make a big splash to get Diggs and that was early in Allen's development. Contenders like Buffalo usually target players to trade who can fit an immediate need and not someone they can have long term.
I think the Pats would consider making a big splash with Thomas if they think he is a system fit and he could be like he was last year in the Patriots system. The only way they would trade for a WR is if he was going to be part of the future and not just someone for this year. Thomas is a guy who could be the #1 WR for the Pats for a decade.
I tend to doubt Thomas will be traded. The Jags are still in contention for a Wild Card. So they are likely not going to give up on this season. The only way they are going to move him is if someone overpays which tends to not happen with in season trades. I could see them potentially moving him after the season and the Patriots could very well be interested at that point.