I have a somewhat different point of view on this one; in my opinion, Carmack has two main strengths. One is to find new and sometimes quite disruptive rendering technology. He usually gets these ideas by absorbing an incredible amount of information from seriously varied sources; from siggraph research papers to airplane…
Battlefield 3/4 and Trials HD are using megatexturing already, and Lionhead developed an engine years ago, too. The most important difference is that BF and Trials are not using fully unique virtual texturing. But the tech has been in use in other titles as well.
I'd say it was two or three years too EARLY. The new consoles would have been much kinder to megatexturing's reputation...also, idTech5 is certainly not the only engine capitalizing on the technique--I'd bet there are other studios taking similar approaches, some even doing it on-the-fly instead of baking it down before…