I don't see how Mystery Dungeon could transition into F2P well, anyway. Shuffle and Rumble World had gameplay that let it work.
Wolf coming back as is from Brawl would be awesome actually, moreso likely since a new Star Fox game is on the horizon. Didn't like how both Earthbound and Star Fox lost a rep in the transition, which is why I'm glad Lucas is coming back next month. Plus, compared to the other "semi-clones", he's the one with the most differences outta the bunch. The only fear I have is his voice becomes obnoxious like how Fox's did. -w-; If the new PMD has any F2P options, it's gonna get a hell of a lot of backlash. Sure the other games it was tolerated for, but this? People were already cautious after Gates to Infinity. Tacking that pay model onto this franchise would just seal the deal right there.
Personally, I don't see your issues with it in Rumble World. I've been having a good time now that I've gotten a chance to play. I had no qualms with Rumble going f2p when we first heard about it, and I still don't. Anyway, besides the point, Rumble's gameplay works in a f2p model, since it's always been a simple beat-em-up game, relaxed and easy to get into. Mystery Dungeon is a different story. It demands a fair amount of strategy from the outset, at the very least much more than Shuffle or Rumble. Nintendo has only released f2p games that would be easy for people to start playing. If Mystery Dungeon does go f2p, I don't see them keeping the level of strategy that we expect intact, which would completely ruin it.
... There's a reason why I put the qualifier well into my first sentence, but I guess everyone wants to ignore it. I have no doubts that it can be done, I just think the gameplay would suffer for it, even more than other types of games.
I love how you assume it can't be done. You can turn anything into a f2p. I, like Pandora, never said it'd end up going well.
There was another updated list with more Pokemon + Fighting styles, but this here's the gist of what I'd like to see. Also Bisharp, Pangoro, and Scrafty.