I've never understood the "glut of [insert position]" line of thinking, unless you're at a point where you have multiple players vying for the same role, and having proven themselves/advanced to the point where a decision has to be made.
Until you arrive at that point, all you have is a bunch of maybes. For as talented as Andersson, Chytil and Howden are, they are maybes at this stage in their development.
I don't consider Nieves to be a long-term challenge for any of those three. If he is, then that's a serious problem.
Hayes is on a one year deal that will either result in him being traded in 6 months, or extended. There's no middle ground there.
Zibanejad, with his pros, cons and everything in-between, is the only top 6 NHL talent signed beyond this season. We'll see how he does, and if he can stay healthy.
Namestnikov and Spooner are not looks to be here long-term, nor are they exclusively centers. So if either has to move off and on between the wings while things get figured out, then that's what has to happen. But I also suspect that was part of the plan as well --- have guys who bring some versatility for the short-term.
Peter Holland is a guy who might fill-in as stop-gap this season. He could spend the entire year with the big club, the entire year in Hartford, or a lot of time shuttling between the two teams. But again, a glut does not Holland make.
The Rangers have enough to vets to plug in holes if they need to.
If this was a team looking to challenge for the Division, it would be cause for concern. But in terms of having guys to step in and take shifts, I'm not particularly worried about that.