Hell, disguises might even be more practical than straight up sneaking.
Crouch has always been some "stealth mode on" button, but it's really unnecessary if they implement proper awareness checks. A careful-walking mode makes sense, though.
As Chris says, a toggle for sneak mode makes sense - actually giving yourself a serious quads workout is unnecessary.
I disagree with the toggle in favor of the awareness checks, and if a manual sneak on/off toggle is necessary it should run parallel to being cloaked. Thermoptic camo is not just deus ex's, it's in many games from halo to fallout to crysis. And we want.