Of course Ps4 had a strong start, it came out 7 years after its predecessor so 7th gen early adopters have been waiting for it for quite long, add it's probably the cheapest PS ever made (considering inflation).
It doesn't mean it will last very long as product, it's clearly not as advanced as Ps3 and 360 were a their launch, and since it starts with a lower price tag, they will have less room for price cuts later. The Xbox One on the other side had a good launch but it's not doing so great right now.
The gaming comunity and developers have become auto-referantial witch means they are based solely on themselves and on their own desires, not caring relations with other realities. The fact, a lot of "gamers" despise "casuals" is a clear proof of that.
The industry needs games and application to attract new generations of gamers, and as long as those applications are seen as "casual games" o C-class games, these new generations of players will evetually decide it's better to spend 2$ for a tablet app rather than 60$ for mainstream game. On the other hand the inner circle of hardcore-smug players will evetually grow older and gradually stop playing.
Plus add the state of the economy in key markets such as Europe and Japan is worse compared to some years ago. I can't see the premise of another growth.







