A big reason id Software signed with ZeniMax Media is to bulk up internally. Traditionally, id has worked on a single project, with other franchises exported elsewhere. id won't be able to work with Raven Software again because its owned by Activision, but Splash Damage, who worked with id on Enemy Territory: Quake Wars, is engaged in a longterm publishing contract with Bethesda, also owned by ZeniMax.
I asked id Software co-founder John Carmack on the phone last week about the possibility of id working with Splash Damage again, even though the studio was moving most development in-house.
"It is the expectation that the major id titles will be developed internally with the id teams," he said. "There's potential for things [with Splash Damage], but we haven't really gotten down to that level of detailed involvement."
So…maybe. But as Carmack has pointed out in a number of interviews, the ramifications of the deal with ZeniMax won't be felt by consumers for many years. A partnership with Splash Damage could very well happen, it's just not going to happen for a while.