I’m starting to be very interested in X-Plane 11.
Actually i still fly FSX. I usuallly fly with PMDG 737 800 NG, using FSPassengers from Bologna Airport (LIPE) to Prague (LKPR), Budapest (LHBP) and Scandinavian airports (all payware stuffs). I also use Active Sky for weather and Mytraffic 6.
Could I use X-Plane the same way?
That is impossible to know given that X-plane 11 is not released yet, and according to the dev blog certain things like navigation will require developer input if they want to retain same functionality as in X-plane 10.
There’s probably a healthy amount of payware and freeware for those airports. There’s plenty of choice to for the 737 and equivalent aircraft in the payware and freeware sections. So I doubt that’d be a problem. Hopefully the weather engine will be sufficiently improved for 11 so that addons wont be needed anymore, although @BeachAV8R knows a whole lot more about this ;).
So in short, yes you can use XP-10 in the same way, and eventually 11 too, although probably not on release day.
There’s no such thing as FSPassengers for x-plane that I’m aware of, though. It’s possible to get AirHauler working with XP10 but it’s not clear whether that’ll work with XP11. Weather add-ons are plentiful though - I think Beach is running about 5 different weather add-ons at the same time to get the effects he wants.The specific ones you have are not x-plane compatible though.
Aircraft and scenery, as @TheAlmightySnark mentions, should work just the same in the new version (though probably not right away).