That whole 5-year thing will create some interesting wrinkles, for sure.
I'd guess that if Demary has the year we hope he has, that he could end up being a mid/late 1st round projected pick.
Same thing goes for Ross...if he takes another incremental step in his play, he definitely could be a late 1st-round guy.
Question will be...is that any better than getting paid essentially the same while being a major-minutes player for a perennial F4/National Championship contender with world-class coaches in front of sell-out crowds for ~35-40 games?
I still remember some talking head quoting an NBA GM or coach about prospective late 1st or even second round prospects that are thinking about forgoing the draft and staying another year, "The more we watch these players the less we like them."
Translation, if a player doesn't improve much by returning, the less upside they perceive, especially with the older players which would obviously be the 5th year ones. These older players, such as Demary and Ross run the risk of not getting drafted or slipping down a round.
So, for some 5th year players that really need a jump in improvement who believe they have it in them, returning might be a good option.
My thought for someone like Demary, whose started a lot of games and logged a lot of minutes, is if he's projected as at least a second rounder next spring he should enter the draft.
As for Ross, who seems to be growing into his body, not logged a ton of minutes who could make a big leap this season and during a 5th, might benefit by sticking around longer.
And for those that are unlikely to get drafted at all, returning is probably a no-brainer if they're offered a nice bag of money to maximize their earning potential during this very short window.
As for the quote above applying to Mullins, he came in as a projected lottery pick whose stock has dropped, and is still very young, can play himself back into the lottery if he improves and lives up to his incoming reputation.
So returning for another year, especially a 5th if the NCAA approves it, is a case by case situation.