I've only recently discovered the game due it being on sale in The Works for £12 (what a steal!!) hopefully it will start getting popular and they will make more expansions.
I don't think they will do any other expansions in English, apart from Knights and Villains, as the game was not well received (because of the poor rulebook and quality control issues with the cards).
It is a shame, but the game is really good I think, as it is, as long as you are happy with the quality of your own copy. It is certainly a bargain at £12. With the FAQs and the user re-write of the rules, plus the other resources on BGG, it is definitely much more accessible now too.
(Edit) BTW I don't think buying Knights and Villains to expand the base game is worthwhile - check out the comments section.