Not at all actually... Interplay was the creator of the Fallout IP and sold it to Bethesda back in 2004. They are also currently in a lawsuit with Bethesda over Interplay's rights to make Fallout Online.
Obsidian has a reputation for doing good sequels to already well-established games.
Neverwinter Nights 2 (sequel to BioWare NWN)
KotOR 2 (sequel to BioWare KotOR)
Fallout: New Vegas (sequel to Bethesda Fallout 3 (not a direct sequel))
I would prefer if TES stay internally in BGS personally. While Obsidian does a good job by improving great IPs, they are kind of a last resort.