Yeah, but the players contracts that are bought with real money will run out the same way. They'll have to keep paying if they want to keep those players. The game will always be dominated by those who choose to throw money at it, but I don't see building your team up for free as a totally impossible task. I'm pulling in 200-300 coins a game playing on Pro with a team of total scrubs (and actually having some enjoyable games), and if you're any good unlike me you'll get much more playing on All-Pro or All-Madden.
For me, I think it'll serve as a pretty good time-waster while I wait for the off-season in my Madden Franchise. I'm just playing it for fun - I have no stake in the leaderboard race.