I think that it will be the same as it is now and will take the place of windows mesenger.

Skype provides a lot more functions than Windows Messenger, especially their video calls and 'telephone' calls. I wonder whether the cost of making telephone calls to land-lines and cell phones will increase or decrease when Skype is taken over by Microsoft. I remember, in the early days of Skype when calls made to land-line phones were virtually free, and calls to cell phone were very, very inexpensive. You could call anywhere in the world for almost nothing. Not so any more, but it's still cheaper to use Skype, to call other countries, than pretty much any other phone service.

By the way, for anyone who's interested, most VOIP phone companies include unlimited USA national and international calling to many countries for a very low price (in the neighborhood of $20/month).

Check out Vonage VoIP Phone Service and Lingo - Home Telephone Service. But I still use my Skype to call those countries that are not covered by Vonage or Lingo.