A few more manufacturers won't end the cartel, they'll just end up joining them.

Remember the cartel used to also include Qimonda (EU, Made in EU and US), Elipda (itself a merger of NEC and Hitachi's DRAM divisions) and Toshiba.

I don't think two more contenders will change much in the long run - in the short term in order to get marketshare they'll play friendly, but 5 years from now CXMT and YMT will just be members of the cartel too.