Bethesda already had Black Isle comeback to make a Fallout game in the form of Obsidian. Obsidian is made up of a lot of former Black Isle Studio people.
Also Bethesda didn't sue Black Isle. They sued Interplay under Herve Caen. And Black Isle didn't create Fallout. Interplay under Brian Fargo created Fallout. Black Isle worked on Fallout 2, cancelled Fallout 3 and when they became Obsidian they made New Vegas.
Yes you did:
What you might not know is that the Interplay that created Fallout 3 was not the same Interplay that cancelled Fallout 3 and tried to make Project V13.
Interplay under Brian Fargo created Fallout, Fallout 2 and Tactics. Interplay that killed Fallout was under Herve Caen who created Fallout: Brotherhood of Steel and decided it was the future and thus cancelled Fallout 3.
Only when Bethesda bought the whole rights to Fallout after they originally bought the right to make three games and came out with the hit Fallout 3. Did Interplay try to make money on Fallout again after Herve Caen killed Fallout. They tried to make an online Fallout which they didn't have the rights to do that. Bethesda sued and Bethesda won.
Point is the Interplay that is around now deserves to respect. None at all.
But the good news is Obsidian now has Tim Cain working for them and I am sure are great friends with Brian Cain. So if you want Bethesda to pay more respect for the orginal creators of Fallout then Obsidian is the company to root for, I hope they get another shot at making a Fallout.