I imagine the PS3 sales will be twice what they were the week before last. Since the Wii outsold the PS2 4 to 1 that week and it should be about 2 to 1 for last week's sales. PS3 sales were about 50,000 last week so I say around 100,000 last week. This is about the same as the PS2 price cut from $300 to $200.
The price cut of the PS2 from $300 to $200 doubled sales and that lasted for a long time. However, that was a huge price cut. Not only was that proportionally twice as big as the PS3 price cut, it was to a price which was percieved as a very good value, a measly 200 dollar. The PS3 price cut is basically from an extremely high price to a very high price. $500 is still too much for most consumers(They'll take out the game bundle and drop the price of the 80 GB to $500 I'm sure). I imagine the PS3 sales should be back to pretty close to what they were within 1-2 months. The release of some bigger titles later should raise it higher than they were 2 weeks ago before the price cut. They don't really have more than a couple of titles that are really huge though. Big, yes, but not huge. I think the only game that will sell better than MP3, SMG, and SSBB is GTAIV, and that game will probably increase 360 sales more than PS3, especially when the price drops to $300. I guess we'll see if Warhawk does well, but with the PS3 having a much smaller user base than the Wii it's going to be hard to outsell MP3 and impossible to outsell the other 2.
The biggest sellers this year for both systems will probably be:
PS3:
Lair
Heavenly Sword
Folklore
*Grand Theft Auto IV
*Warhawk
*Ratchet and Clank
*Guitar Hero III
*Assassin's Creed
Mercenaries 2
Uncharted: Drake's Fortune
Unreal Tournament 3
Wii
*Metroid Prime 3: Corruption
Disaster: Day of Crisis
*Guitar Hero III
Zack and Wiki
Battallion Wars 2
Wii Music
Manhunt 2
*Resident Evil: Umbrella Chronicles
Soulcalibur Legends
*Super Mario Galaxy
NiGHTS: Journey of Dreams
*Rayman Raving Rabbids 2
*Mario & Sonic at the Olympic Games
Fire Emblem: Goddess of Dawn
*Super Smash Bros. Brawl
No More Heroes(might be 2008)
I starred the ones that I predict will sell the best.
The Wii's games should keep it sold out. The PS3's will probably give it a decent holiday season although I think as long as the 360 drops its price it should beat the PS3. I'm not as familiar with the 360 list since many of the games it's relying on are originals, but most would say it's at least as big as the Wii's lineup.