There's only 10% difference in hit rate between 2nd and 3rd round TEs. And 3rd through 5th all have similar hit rates. Given well rounded TEs have arguably the 2nd steepest learning curve (QB is first) when transitioning to the NFL, early impact TEs are pretty rare (unless they are limited to receiving and not so much blocking). In short, if you're not going 1st round for TE (which teams rarely do), rounds 3-5 are just fine.
I also doubt the FO sees TE as dire right now (enough to use a second). They just locked up Doyle, and MAC was improving and tracking well last year before his regression (really lack of targets, not his regression) this year. And, probably most important, TE is a devalued position (similar to LB), are are one of the best values in FA. That plus the steep learning curve (longer development) make FA TEs more attractive than drafting an early TE.
In terms of talent, this isn't a great class for top end TE talent anyway. I don't see any TEs projected in the first round. Only 2 that might go in the 2nd, but I'd actually bet on only 1 going mid to late 2nd. Then there are 2-4 that will go 3rd or 4th. There are several hidden gem type that could go 4-6 IMO.
I think that if Luck does not return this upcoming year, he will never return.
Luck is a very smart guy. If he's away from football for nearly two years, no doubt he would have found something new to focus on and devote his time to.