Oh, I'd be okay with what you suggested, and it would be a bit easier than combining city and team names together. I'm okay with players having just last names too.
That said, why not a long list of potential team names? I'm not sure they could figure out way to use "49er(s)" but maybe "niner(s)" could be used? Or allow us to choose a pronunciation, but spell it differently? A sample prison team called the "Stealers" becomes the "Steelers"?
I'll be perfectly happy to use the "Miami Sharks" instead of "Dolphins" if need be, and I'd like to create an "alternate history" type NFL anyway. Or a "What if the USFL survived and the NFL folded?" kind of league.
The ONE feature that 2K can offer that Madden would be hard pressed to match? An online start-up league. You pick how many teams, each owner chooses a city, team name, logo, colors, and then you draft of bunch of generic players or choose from a customized list. Let guys play for a set number of years/seasons (3,5,10) and award points for making the playoffs, winning a championship, divison, etc. See who has the most points at the end. Add in a draft every year (based on record, random for the first year) and some limited player trades and draft pick trades too. I'd only limit the years played since guys would eventually drop out, as happens.
Now find me a football gamer that doesn't want ANY PART of a game that does all that...