While DL might be in the "let's make them an off they can't refuse" position, that "offer" is probably more like a codeshare and/or an alliance agreement. Anything is possible though.

http://www.ajc.com/business/delta-ey...ls-778037.html

VS' current partnership with some Star Alliance members doesn't necessarily mean they wouldn't join up with Skyteam. After all, CO was partnered with DL for many years and suddenly CO and UA merged.