It seems like Bethesda is getting pretty desperate now. Unfortunately, their lawyers waited way too long (7 months knowing full well it was being developed) to file their restraining order, which is what undid them in the end.
I think they're getting really desperate because they want to start working on Fallout 5 soon. It's a highly successful IP after all, and they don't have much else planned. In the original Fallout IP sales contract, as soon as Fallout 5 is developed by Bethesda, the IP is reverted back to it's original owner: Interplay.
They have Fallout 3, which has 5 DLC packages. And Fallout 4: New Vegas (which I suspect they didn't call FO4 in the hopes that it might help them in court when the time comes) now has 6 DLC packages. The DLC is being used to buy them some more time, but they can only keep shoveling out crap so far.
Now, I suppose they could create a "new type" of "expansion pack" that completely rebuilds the graphics and gaming engine. Fallout 5 could in fact just be an "expansion pack" to Fallout 4 for example. :) But then there would probably be more legal fights about what exactly constitutes a PC game and an expansion pack.
I think Interplay is just playing the long game. They might not have any money, but they're thinking ahead and they just need to hold out longer then
There's probably no real development happening, and Interplay has no serious plans to produce a Fallout MMO, so they're just waiting for Bethesda to fold and finally purchase the Fallout IP unconditionally with an outrageous price tag. This recent legal game is just demonstrating how desperate and unplanned Bethesda is in dealing with the situation. I think, in the end, Bethesda will completely own the Fallout IP but they'll pay an arm and a leg for it. Would be funny though if Interplay got the IP back, and sold it to their competitors.
* Correction: Take-Two published some of the Elder Scrolls, but not Fallout. Fallout was self-published by their Bethesda Softworks division. Although, Namco Bandai published FO4 New Vegas in EU, AU & NZ.