Tiger finishes with how many major titles...

I think 18 is gettable, I would be shocked if he didn't reach 16.  I say he'll tie Jack.  His biggest challenger at the moment would appear to be himself, even as there's a good dozen others just as capable who aren't as scared as his field was 15-20yrs ago.  

He gets to play Augusta with these guys again & again, + he's got some fairly favourable tracks to compete on upcoming.