This is a very different world from the one in which IE6 rose to dominance. We're in no way in a Webkit monoculture right now – Trident and Gecko aren't going anywhere any time soon!

Specifically addressing Opera: the smaller-audience engines that have had their chance but not done much with it should be left behind, making room for new small players to step in and take the reins. I can't wait to see some new players in this space.