Speaking as an NYCFC fan and a fan of the Cosmos, I have great respect for the Cosmos for having refused MLS's terms to join the league (which led to that opportunity going to CFG, and ultimately brought about the creation of NYCFC), and for their having given it a go in the NASL. It was very important to them to control their logos and marks, and to be able to independently sign players.
Nevertheless, it seems likely that that approach has run its course, as the NASL's best cities continue to be picked off by MLS (Montreal, Vancouver, Atlanta, Minnesota), by the USL (Ottawa, Tampa Bay), and perhaps even by a possible Canadian league (Edmonton). The future of that league is shaky at best. If there is something to the rumour of CFG putting up an offer, then perhaps the Cosmos' owners will figure that this is the last chance for them to recoup their losses.
Even though I support an MLS team, I strongly dislike the league's single entity scheme, which is a means of preventing players from establishing their true market value. The traditional independent-club model was worth fighting for; so it would be sad to see the standard-bearers of that approach go by the wayside.
If the end is near for the Cosmos as an independent club, they go out with their heads held high. They fought the good fight, but could not overcome conditions that were beyond their control. The main issue, the lack of a stadium location in New York City, afflicts NYCFC as well; but, of course, we have Yankee Stadium as a more-than-adequate Plan B, while the Cosmos' Plan B of playing at a Long Island college lacrosse field has not worked out for them at all.
Maybe a CFG-owned Cosmos team could more easily find a home somewhere within the City. Perhaps they could play at the stadium of the Yankees' minor-league affilliate on Staten Island. The Cosmos have already played several matches at the Brooklyn Cyclones' stadium; but for a CFG-owned Cosmos to play there would require some Yankee-Met detente, which could be tricky.
The Staten Island park has a natural grass surface, and so could conceivably be converted to a soccer pitch by means of sod, as is done at Yankee Stadium. By contrast, the Brooklyn stadium's surface is Field Turf, with the "dirt" of the baseball diamond being made of the same material as the "grass", but coloured brown. For soccer this looks as bad as the lacrosse lines on the Cosmos' current home field at Hofstra.
Still, the Brooklyn park is in Coney Island, which is a much better place to hang out than Staten Island. Either way, the Cosmos having a permanent home within New York City in an appropriately-sized professional stadium would outweigh all drawbacks; and, if affilliation with NYCFC accomplishes that, then I'd be in favour of it at this point.
I have often said that fans of NYCFC and the Cosmos should ideally have a mutual respect and a friendly rivalry. Each club has a legitimate approach to authenticity -- the Cosmos by remaining independent; NYCFC by being owned by the group that also owns one of the world's most ambitious clubs. The two fan bases are united by our attraction to this authenticity, and also by our contempt for the Red Bulls and for the lingering stink of the early MLS that they will forever carry.
In the rumoured scenario in which CFG buys the Cosmos and makes them NYCFC's affilliated second team, most likely in the USL (thereby continuing the trend of MLS-affilliated farm teams in that league), this would be a fine way for the name to live on in the current climate. The Cosmos would then actually be in the NYCFC family; and I as a fan of both teams could certainly live with that.