Tatar has played in 345 games, Nyquist 337. Both are in their late-20s. They are vets by nearly any definition, and in 3-4 years they will actually still be close enough to their primes to support the younger guys coming up. In 3-4 years, you're looking at Helm and Abby both nearing their mid30s and Nielsen will be on the wrong side of 35.
Agree with a lot else that you said, but guys like Tatar, Nyquist, Sheahan, Glendening, and Dekeyser (and, frankly, Mrazek) need to be the guys taking on those leadership roles. They are the right age for it. If they aren't able to take on those responsibilities I think that speaks to bigger problems.
We're not rebuilding because Kenny isn't building this roster or this organization to be rebuilding. Yeah, he traded some guys when we were clearly out of the playoff picture. He's also loaded the roster with vets, and then went out and has signed some more mediocre vets (while reportedly pursuing others), and talking about making the playoffs being the goal.
Yeah, the Wings might just be a horrible enough team so that they will bottom out again next year regardless. But that's not rebuilding. That's mismanaging his resources to the point of the club imploding. If this club was rebuilding, that would be the purpose of Holland's moves. Outside of near delusion, I can't see any realistic argument that Holland has rebuilding as the purpose behind what he's done.