And who said it would come out with an ending? New Vegas not having play after the end isn't a failing. The reason why there isn't play after the end is because there are so many possible endings and it wouldn't be a matter of a "simple patch." What if you played as the Legion and took over the Mojave? There wouldn't be any other factions but for the Legion. Copy and paste for all the other possible endings.
Also are you even aware there are other Fallout games besides Fallout 3 and New Vegas? All the Fallout games end BTW, even Fallout 3, but Bethesda caved and slapped on Broken Steel which breaks Fallout 3's whole plot. Fallout 2 has the option to do a for fun play after the end that isn't canon, but there is really nothing to do once done.
Also as been said you can completely avoid the main quest line and even if you want to do some of it, there are many options to undo what you did. Play Lonesome Road and at the end you have the option to have your reputation with every faction reset to neutral as if nothing happened.