Based on the poll, it seems a Slimline PS3 priced 299$ will do the most good.

On the gaming front I think Home and easy to pick up and play games like LittleBigPlanet will help considerably.

1) I think we are still very early into this generation (still the PS3's first year in Europe and most parts of the world), quite a few people who bought a Wii come from a more hardcore GameCube fan background. The previous generation the PS2 sold many times more than the Wii sold so far. It's not a sprint race.

2) The PS3 and Wii have very little games overlap, of the top 20 games for both platforms only Guitar Hero 3 overlaps. It may eventually be interesting for casuals to own both consoles.

3) If industry predictions and outlooks are correct, high definition (visual + audio) will play an increasingly important role this generation of home consoles. So the PS3 demand should get stronger over the years.

 Only with a $299 price tag + free games (modchips), thats probably the main reason of the success of the PS2...

More sales, more games, more sales... 

Wii easily owns the casual games market this generation - casual gamers (who buy ONE console only) will not buy a PS3.

i thought it was interesting that according to that poll blu ray winning the format war was a very small motivation to buy one. looks like they'll have to have another price drop to spur sales if that poll is to be believed.

Fixed

I had to add X360, because Shams you started to sound PS3-bias in that statement.

Kids are better represented amongst the Wii userbase than on the PS3 and I would agree they won't likely get a secondary console until available at very low pricing which is going to take many years. IMO it's Sony's job to try to push their (young) parents into buying a PS3, I think that's entirely feasible to some extend.

How many people amongst the Wii userbase would you clasify as "casual gamers" or "Nintendo fans" upgrading from the discontinued GameCube? My personal prediction has always been that the PS3 will outsell the Wii in 2009 and onwards.

The PS2 was so popular because:

1. It was affordable to the average household from day 1 ($300), and after 18 months was affordable to the majority of households ($200). (Note: American/European timeframe)
2. It lacked strong competition until it was in a "dominant" position; by the time the XBox and Gamecube appeared on the market Sony had sold nearly 20 Million consoles and their big named games (Gran Turismo, Metal Gear Solid, Final Fantasy, and Grand Theft Auto) were being released at an alarming rate.
3. People bought a PS2 because their friends owned a PS2; when a group of friends were sitting around talking about videogames they tended to talk about PS2 games because they all owned a PS2, their friends who didn't own videogame systems tended to buy a PS2 because of the (overwhelming) dominance of PS2 ownership of their friends.
4. DVD was the hot product on the market BEFORE the PS2 was released; DVD was launched in 1996 and the combination of no additional hardware needed to gain the benefit of DVD, the massive improvement in convenience of the format, the obvious improvement, and the release of several visually "amazing" movies (the Matrix and the Fifth element to name a couple) made DVD the hot product of 2000, 2001 and 2002 (when it eventually took 50% of the market in late 2002).

None of these factors apply to the PS3, it started at far too high of a price and will (likely) be out of the price range of most consumers for the majority of the generation, it is facing two tough competitors who have the lead on it, the PS3 is not the hot gaming system so it doesn't gain the benefit of everyone owning one, and Blu-Ray will (likely) not match the popularity of DVD (at the launch of the PS2) until 2010 or 2011.

@ HappySquirrel

Do you not understand the concept of a combination of factors?

The Playstation launched against a $500 Sega Saturn which (with inflation) would be similar to an $800 or $900 system today, Nintendo offended all third party publishers and launched 18 months after the Playstation with a difficult to develop for system which lacked a key feature developers wanted (CD audio); it was only after the N64 launched, Final Fantasy VII was released, and Nintendo had the worst  game drought ever that the Playstation really dominated.