I think it bears debating how it would be different from signing Villa. Yes, DV was younger, but he was at a relatively similar stage of decline (was not a sure starter for Barza or Atletico anymore). Silva has been one of the best players in the PL (and the world, really) for the longest time. His pedigree is second to none. Maybe he has less star power than DV had because he's not a striker, but OTOH casual American soccer fans pay much more attention to the PL than LaLiga, and also those who ever think of LaLiga would probably focus on the Barza v Real, Messi v Ronaldo dichotomy, whereas PL allows for more diverse allegiances.
I think at this point we cannot imagine our club without DV, and part of the attendance success of 2015, 16 etc. was due to novelty value. But to think that Pirlo, Lampard or even DV by themselves would bring substantially more butts into seats that Silva misses the context, which is: it is 2019 and people have tired of NYCFC. We still play in a baseball stadium, the brand is stale. Playing our best soccer ever under PV our attendance was down, and again playing very well currently under Dome it is even further down.
The only way to turn that tide would be to appeal to Hispanic fan base with a 100% flash-rather-than-substance move such as bringing Chicharito or Falcao. Literally a rebirth of the brand in terms of the shock value. Even Aguero would probably not cut it, although he would be better soccer-wise and would score like a maniac. I am not sure Argentina would move the same amount of fans Colombia or Mexico would mobilize.
So I don't think the problem would be Silva per se.