I'm guessing that the coaches would certainly like to get Devine down to 330 or so. I'm also guessing that the telling factor here will be how well he plays on the field. If he does well at 359, then I'm pretty sure that Coach will suck it up and play him. If he can't then he'll get platooned, just like last year.
There really isn't anything magic about weight. True, most players could do with less of it, provided they aren't losing muscle (as was pointed out above). But there have been plenty of great football players who were natural butterballs. My favorite: Frank Nunley, the great '49ers LB. His nickname was "The Fudgehammer" because, as one of his teammates said, "He's sooooo soft and he hits sooooo hard."
I expect that Shamire will start next year, no matter what his weight. How long he'll stay in is up to him.