Ok so assuming that the Hungarian elite gets smashed.. How would this affect the Austro-Hungarian Army, Airforce and Navy could it be comparable to the strenght of the German Empire, or perhaps a bit weaker ?
Depends on when it happens. Breaking the Hungarian aristocracy would have massive effects on the Empire, even in the short term, let alone the long term. There's also the question of what happens after, which direction the Empire takes would be just as important in determining what happens later.
If it happens early enough, you could see Austria's economy grow even more (OTL, IIRC, it was second to Russia with regards to economic growth).
The Army would certainly be stronger and better equipped. Not Germany, to be sure, A-H had neither the population or economy to maintain an army on Germany's level ... and it wasn't nearly as focused on quality and discipline as Germany was, but much better than OTL and with a lot fewer issues.
The Navy and the Air Force, you're pretty much looking at OTL developments. Aside from Hungarian wrangling over authorizing funds the navy was never really the focus (the air force, what air force?). There wouldn't be a dreadnought slipway in Fiume and it's possible that what would've been the
Szent Istvan (IIRC, the proposed name was
Don Juan d'Austria) would be operational earlier, giving the K.u.K. Kriegsmarine 4 dreadnoughts at the start of the war ... not that it would affect things, the navy would still be dwarfed by the British Mediterranean Squadron and the French Marine Nationale.