I'd like to think it will come out within a couple of years. I guess it depends whether Axl wants to use some of the older material and add in the current lineup like he did with Chinese or make a completely new album with the current band. There's probably tons of material from when they were recording Chinese still around [Bach confirmed this] and it would be great to hear. I think the main reason why Chinese took so long wasn't just Axl being Axl. There were issues with the record company (I read somewhere that there was a version of Chinese finished in 1999 which the record company rejected), Buckethead leaving also must have delayed things. Zutant said that there was also a pretty much finished Chinese in 2002.
I guess they'll do the 09/10 world tour then go back to the studio, patch up some more of the older material and release it. It seems as though most of the problems Axl seems to be having are with the label. On another note seeing as how KISS and Journey have included their greatest hits rerecorded by the current lineups with their latest albums, does this mean that the time is right to release the rerecorded Appetite with the next album?