I think Guts losing both his eye and his arm are pretty symbolic. Note the whole episode called "The Right Eye's Last Light" where the last thing he sees is Femto raping Casca. It's almost a bitter reminder and a bolster to his vengeful resolve to only have one eye. So no, I don't see him getting his arm or eye back because it doesn't fit with the storyline. Also note how guts is still getting constantly hurt and adding to his collection of scars, ie the slash across his chest from Slan and the heavy burn marks from Gashinka.