I dunno it sorta seems like ND are taking more time on each game.

Uncharted 3 released in 2011. The focus was then TLOU, which released in 2013, but it was suggested Naughty dog were focusing on two projects at a time.

And it's safe to assume Uncharted 4 was in early stages by 2011/12 (Amy Hennig/Balestra/Wells had to do something)

So this gen, from them:

Uncharted 4 2015
TLOU sequel (almost definitely guaranteed) 2017?
PS5 2019

This gen will probably be shorted due to the exponential growth of technology now vs technology around ps1/2 era.

If you include TLOU:R, since it was in house and in its own right a ps4 developed game, then three. Uncharted trilogy then 5(6, 7?)

But do you think taslking about original games, ND will manage three or 4 games this year?

This gen won't be shorter. Sure, hardware growth is exponential, but it makes little difference at this point (Diminishing Returns)

I think they could make 3 or 4 games this gen.

Given the learning curve for the PS4 is far shorter than the PS3 it's conceivable that they'll be able to do more in the same timeframe, especially when they get past the initial hurdle of getting their new engine in place. After that it'll be down to just making games and improving engine efficiency/GPU compute tricks.