foolish? i wouldn't think so. you could probably wait until closer to the ps3 launch date as i'm sure they will be dropping the price on the ps2 sooner or later.
i have a 360 and sold my ps2 and all of my games with it on eBay a pretty good while ago. i was thinking about picking up a ps2 again sometime but like i said i'll probably with until the ps3 has launched.