I have been playing near 40 hours... I am level 25... I have made contact will all the different major groups and I have informed yes man of that... Now the quests I have is to go in and destroy House... And go into the underground facility beneath Cesaers fort... I am wondering when is kind of the "point of no return" where you commit to the last battle... I have no desire to support Legion, NCR or House.

You'll get an on screen notice.

Once you get far enough in doing quests for your faction of choice, whether that be for Yes-Man, House, NCR or Legion, a big pop-up window will appear and tell you that you've reached the point of no return and can either proceed or go and prepare some more. As long as you don't get too far in the main questline you wont reach the point of no return. So after you kill House, and after you go into the underground facility, and after you do a few more quests after that, only then will you reach it.