In the nineties, the oldies consisted of music primarily from the 50's and early 60's - therefore, it is reasonable to assume that in 2010, artists from the 70's and early 80's. This might include REO Speedwagon and Boston.
An Oldies artist would be any of the hair bands such as Poison, Scorpions, and so forth. It has been almost 20 years since these artists were popular alone and even though they are still being listened to, a whole group of teenagers were not around when their songs were popular.
In my opinion, by the year 2010, Bon Jovi, Led Zeppelin, Def Leppard, White Snake, Queen, Quiet Riot, Depeche Mode, Enigma, David Bowie, Elton John, Rick Astley, and Madonna will all be considered oldies artists.