I'd expect him to burn himself out and walk, assuming he's not chucked out for doing something stupid beforehand, which might be the more likely scenario.
Sadly for Marco, burning himself out will probably apply to his life in general. Most people in that situation have developed some sort of talent in order to reach that level of excess and have something to fall back on in terms of self-worth (and I don't mean in the financial sense) but it must be obvious to all that this guy has got serious problems, possibly among the most serious we've ever seen on Big Brother.
You could put it down to him being so young and that time is still on his side but I can't see anything applying the breaks there other than something life-threatening.