Google will build a avatar enhanced social / virtual world with 3-D Graphics.
Why do I think they would they do this? If you watch certain Google Tech talks, it makes sense that they'd have some Second Life envy. Google also would like to build services that are popular with the kids, i.e. the 15-22 year old demographic, which is one of their weaker areas.
When this service comes out, it will probably be panned, and disliked by the cognosceti who think Google should stick to its knitting. But I think advertising in virtual worlds is something they will want to figure out.