Good question...
That's a good question...I guess we'll find out. I think that Kevin has the ability to be the leader if he decides to start asserting himself. I don't think it's really in his nature, but I think he could do it. I saw a bit of that in the "let's go home" game-winning shot that he hit last year. He's developed a little bit of attitude, and that's a good thing.
Ron is definitely willing to lead, in much the way the first lemming jumping off the cliff says "follow me, everyone!" I'm sometimes scared of what he might be telling them all to do, but it seems to be inspirational in many ways. The other problem with Ron, obviously, is that he can be a bit of a loose cannon, deciding that he knows the game better than everyone, including the coach. In any case, as the OP wrote, we don't know how much the other guys will listen to him now, and at some point, he won't be here any more.
Garcia is also willing to lead, but I don't know how much the other guys listen to him.
Beno is probably the best choice, just because as the PG, he's also the most logical person on the court to make decisions about what happens next.
Here's the part I'm not sure about: does a team need a vocal leader to thrive? Who was that leader before Ron got here? Was it Bibby? I don't know...once Ron is gone, we may find out.