If Kyrurem can turn into black and white Kyrurem, what kind of types would it have now? Ice/Electric/Dragon and or Ice/Fire/Dragon?

Or would it have the same type or Reshiram and Zekrom's types? 

hmm, good point

I love unique type pokemon (Krookodile!), and this could bring the number of possible types sky high.

God, that would make it all even more confusing. The strengths and weaknesses of all those Pokemon versus others with 3 types would be agonizingly convoluted.

Well, the only thing I can imagine strange is that some pokemon will have 8x weakness to some types... but that's ok, since 4x is already a pretty guaranteed 1 hit death anyway..

But yeah, probably there's lots of "break-game" things that might happen. Let's wait for the opinions of the especialists here.

Highly doubt it. Giving Kyurem a third type would result in an incredibly overpowered type arrangement. Including STAB bonuses would just make Kyurem too difficult to balance unless they just nerfed his stats or movepool to the point that he would be unplayable in any sort of meta-game. Kyurem already sucks, so I'd hate to see him remain in such a state.

The idea of expanding Pokemon into three types is an interesting concept, but it wouldn't work in application. It is already hard enough for Gamefreak to balance 600+ Pokemon as it is, but taking into account all the crazy type arrangements, many of which could become essentially untouchable, would result in something slipping through the cracks unnoticed. Besides, players have a hard enough of a time keeping track of the types for the pokemon as it is, so adding third types would just things all the more difficult and tedious.

Unlikely. If Black and White 2 were Gen 6, then maybe. But we're still in the same Gen, and I don't think GF will actually introduce such radical stuff halfway into the Gen 5 cycle...

The only thing I want is new starters...

Unlikely, They will supreme one type to put other, like Kyurem is Dragon/Ice, Ice type desapear and appear the other type

It would be better if they introduce a new type of pokemon, although I can't think of any other element/type of the top of my head.

I would love seeing his new forms as Ice/Fire and Ice/Electric.

Making it Dragon/Fire and Dragon/Electric would be too silimar to Zekrom and Reshiram.