I think the question "Has NL Texas Hold'em been killing poker" has to be asked at several levels and possibly get different answers in each case (internet poker / live poker at professional venues legal or not / live poker at homes, and specify between cash and tournament in all of the above).
Also, a distinction has to be made between the game per se and the betting structure (limit / pot limit / no limit).
I can only have an opinion about home cash games.
In these, a NL betting structure is unnecessarily violent, IMO. Poker is by definition a violent sport, something like boxing with money - no need to upgrade it to kick-boxing among real people, even distantly acquainted to each other, who attempt to have a good time under the same roof for some hours.
Game-wise, although I acknowledge that any specific game should be played for at least one orbit, to "yield its aroma", I could never play the very same game all night without going nuts (even if dealt the nuts
).
There are several serious, not-that-extreme variance, hold'em versions, let alone stud games.
So, my pick would be dealer's choice among a limited array of "certified" or previously agreed upon hold'em versions (Texas, Omaha, Pineapple etc) and orbits of stud, everything Pot Limit at the most.
An appropriate Maximum buy-in for any given stakes is also of paramount importance for player comfort and level playing field.
Tournaments are, of course, a different story.