I would be a little leery about buying a new console this year based simply on launch or near-launch exclusives. If this generation runs another 7-8 years, the exclusive landscape can change dramatically over that time.
If I had to guess I'd think with everything now on an x86 landscape we'll see a lot less exclusives this time around - the games will be easily ported to the XB1, PS4, and PC triad. Just my wild supposition, though.
Architecture doesn't have anything to do with third-party exclusives. That's economics. The reason why Titanfall isn't coming to PS4, for example, is because Microsoft is paying EA not to port it, and that's almost certainly a good business decision. Likewise, there was never any technical reason why Konami couldn't have ported MGS4 to the 360. They didn't do so presumably because they signed a contract with Sony precluding that.
The reason why you won't see many third party exclusives is because both consoles are going to have pretty large install bases, which makes it really expensive for a developer to ignore one console. Unless Sony/MS is providing some development assistance or something like that, it's going to be tough and/or expensive to bargain for exclusivity.
First-party studios are a different story, obviously.