I just want to confirm what Ezer'Arch said is 100% correct
Forge is very important to me, and I follow its development and the blogs of its creators
Lex is working on forge 1.8, comments from my son ( who works for Microsoft, but is not near the purchase of Mojang ) lead me to believe that at least as far as 1.8 there will probably not be an issue, beyond that it is difficult to say.
But as 1.8 is currently the definitive version of Minecraft, I think we have a strong future if they get forge to that level.
I am thinking of 1.8 as Mojang's Release version of Minecraft
We dont know what Microsofts versions of minecraft will be, or if we will even use them, that is a future discussion.
But if we get Forge for 1.8... then Modders can stop updating to new versions of Minecraft, and just work on their Mods for the definitive version of Minecraft
As you can tell Im a glass half full kind of person, looking for good, in bad, it might even be a good thing.. that there is one version that folks do Mod work on, and dont constantly have to udate to a new verion.