yes, the metagame will certainly shift (though not as rapidly now that 1.x season is over). There are plenty of decks that can feed on Gro decks (oath comes to mind) to beat it back into it's place. Also, although supergro was built to beat miracle gro head-on, it's a little slower, so it's weaker against a lot of the control decks that the original (or Long-style) gro eats for lunch. The GP metagame moves in quick and violent swings--gro did very well at Vegas and that Asian GP when trick was still popular; pretty soon much of the field was playing it and trick was dead; next thing you know people had versions specially tweaked for the mirror (supergro) or were playing decks to beat it (oath). Within a couple more GPs, the gro fad would have passed and Miracle Gro would have settled out as one choice out of many. Gro just doesn't have the raw power (think original trix with necro) that can let a deck remain a clear #1 despite everyone playing it or playing to beat it. Super-Gro should probably disappear entirely once the gro wave recedes and its slowness become more of a liability. Even trick will eventually pop up again once it is no longer getting hated left and right. In the meantime, I'd play oath until the field (everyone you know who's playing super-gro) catches on.