For something to have a "metagame" it needs to at least be ascertainable within a reasonable time frame...
Eh, not necessarily so. I'd class Achievements/Trophies systems as a metagame, and they have neither a limit (well, outside the number of games in existence) nor a time limit on how quickly you have to garner them.
Oh, and I did say in my original blog piece that I'm fully aware that total knowledge of a perpetually growing roster is an impossible task. This whole thing is, as you say, my own takeaway from Salty Bet.
@fredchuckdave: Nope, because as I'm saying, the metagame isn't so much about the money. That's the actual game, and is just an indicator of how well you're doing at the metagame of having total knowledge of all the fighters.