Nothing will happen! they'll merge together later on, or i guess they are already merged with Bing's database.
MSN & Live search are already merged into Bing. If you try to go to live.com, it will redirect you to bing.com. To access Live id go to home.live.com. You can go to msn.com & search. But the search will go through Bing.
It is obvious that with the launch of bing, all of their other products in the search segment will die a natural death by either merging them with Bing or getting discarded completely! Regards, RightMan
MSN and LIVE are already fused into Bing and i think later on, i guess few years later,these three search engine will be merged again to from another one. i hope it wont happen again and again.