Hmmm... I've been thinking of a plan for Sony to regain market leadership, but it's really hard. They need to take more risks than they have ever made and they need a BIG campaign, a GOOD one this time.
Before PS3 launched it should've been fairly easy for Sony to hold it's dominance. They could've focussed on PS2 for a couple of more years, outselling the 360 and keeping Wii from creating too much momentum. Then they could have launched the PS3 a year or so after the Wii and 2 years after the 360. It would launch at a low price, with insane hype and with two competitors exhausted by PS2.
But no, Sony decided to go the 'mine is bigger than yours' way, fighting Microsoft, forgetting about Nintendo's last resort plan. In fact, if it wasn't for Microsoft, the PS3 would've been much less expensive, less hi-tech than the current PS3 with a much higher chance of succes, imo.
Microsoft HELPED Nintendo slipping past Sony. While Microsoft and Sony were in their battle of technology, the underdog climbed to the top.
But for a way of regaining dominance agian, current situation? Make sure Wii doens't have any more exclusives, lower the price to Wii's pricepoint and introduce a casual gamer attraction plan. How? That's up to Sony. When? Never, as long as Sony keeps thinking high horsepower wins everything. They still think that, as they are happy to state that the Wii will stop selling in a few years because 'teh graffixx suxxorz'.
Future is bright for Nintendo as market leader.