Wilson, Moten, and Fletcher will 100% leave.
Mensah imo is definitely not a lock to enter the draft. If he's not a likely 1st rounder (Which arm strength may hold him back from), his pay is 10000% maximized by staying here another year. Like its not even close. And we would obviously value him as the highest paid player in CFB next yr tbh. Especially to maximize Toneys 3rd+final year.
Justin Scott is likely to leave imo. I think even if hes viewed as more of a 2nd rounder post CFP, he will still declare. Ultimately his talent and Likely athleticism will have him as a riser in the draft process. As of now Echoles, Stone, Moten.... Right now he might be more like the 4th DT? Maybe 5th if Amauri Washington... I think unless he's getting feedback he's more like 3rd rounder, he'll be gone. BUT we gotta do what we can to retain him. DT is already looking like potentially the most importantant or 2nd most (after OT?) non-qb portal need.
Samson is the biggest decision along with Scott to returning or not as far as possible. IF he gets feedback that he isn't an NFL OT after just 1 yr, I do actually think it's possible. After all he will only basically have 1.5yrs of experience after this season. And it's not like he's been perfect. He still needs a lot of experience especially if he really wants to be an OT at the next level and not just immediately be pushed inside.
Lightfoot should/will return. Gameplan should be for him to gain another 5-10lbs and go next year. I mean if he's a clear 1st, yeah he should probably go, I'm just very doubtful he will be after 1 real yr of film especially given his weight currently.
O'Connor at his current pace is gone to NFL especially since this is his 4th yr (unlike OJ+Lucas).