Exactly, sorry if I did not use the right word (not native english speaker). I did not know that "keep" was so binary. With keep stealth ability I meant that it

Exactly, sorry if I did not use the right word (not native english speaker). I did not know that "keep" was so binary. With keep stealth ability I meant that it may not keep all it's properties to the same degree as today and some of them can decay. For example as you mention about the distance for detection from a single radar in normal flight.