Roland Garros could theoretically return to its traditional role as a haven for one-Slam wonders and clay specialists. From 1989-2004, 12 different players accounted for 16 Roland Garros titles...only Bruguera (2), Courier (2), and Kuerten (3) won it more than once during that time.
Realistically, it will likely return to something more like the 70s and 80s, when you had a mixture of guys like Borg (5), Wilander and Lendl (3 each) with a mixture of one-time winners. Rafa created an unusual context that we're unlikely to see again for any Slam. I could see Carlos winning it several times, but more like the Wilander/Lendl (3 each) to Borg (5) level.
The point being, we're likely to see some "non-great" Roland Garros winners. But of course this is true of the other Slams, as well. The Big Three had them on such lockdown from 2004 to 23 - a full 20 years - that it is hard to imagine anything different, but really that was an anomaly. I would argue that for a time at least, the Connors-Borg-McEnroe-Lendl era had similar elements of dominance, but not quite to the same extent or length.
