Like I said in my previous post, I gave an "academic" example only in order to show that a Stealth aircraft will always be harder to detect than a non-stealth one no matter what radar technology will be invented in the future.
In my "academic" example I admit that I didn't take the Earth's curvature into the account (thanks for pointing it out). And I could reduce the range from my previous example from 800km to a more realistic 400km and the end result would be the same/similar.

Also yes, in the case of the F-35 (the most advanced stealth fighter aircraft) Stealth won't be used on it's own -> The F-35 will be able to use it's radar (as an antenna) and internal jammer to jam enemy radar sources (similar to a dedicated jammer aircraft) or of course use data from other sources (thru data-link), etc, etc...

EDIT: Actually I'm curious to know if it's possible to employ some kind atmospheric bounce effect in order for a radar to be able to detect aircraft at ranges that exceeds the Earth's curvature as pointed out by MK_PL?