3DS will have a solid sales this year, but the PSP had more longetivity in the end. And especially if the rumours of the new Nintendo console are true. That said, I think the N3DS should give the console a bit more life. Hopefully it ends up around GBA's and PSP's numbers.

Good support = good sales

Had a good first-party game support imo but third-party game support and marketing were a disaster (comparing with PS2). It also couldn't read DVD's. 

It not suprising that PSP had those amazing sales and 3DS will probably never top those sales

Splinter cell, Prince of Persia, Beyond Good and evil, Rayman, Call of Duty, SpiderMan, 007, Resident Evil, Tomb Raider, Need For speed, Fifa, Madden, NBA, Metal Gear, Mortal Kombat... all with a better graphics than the PS2...

The same for

Good support =/= good sales. 

No GTA, no Metal Gear Solid, no Final Fantasy, no Tekken, no Street Fighter, no Kingdom Hearts, no Dragon Quest, no good WWE game... Too few good games on Gamecube / Xbox.

But you can't say that the third party support on GC and XBOX was bad... of course not like PS2, but that is another story.

The super sales gap is not for the games, just for the super marketing of Sony.

Interesting and is validating my theory, that 3DS took the market of the PSP, while nobody took the market of the DS. That's not true completely, some PSP-users got a Vita, some core-Nintendo-fans stayed at 3DS (Pokemon-fans will have been gotten a DS and a 3DS). But mostly 3DS took over the users of PSP while abandoning the casuals that bought DS.

The only difference is, that 3DS is going faster. Sales grew faster, and it is now a year ahead. 14M in PSP's fourth and 3DS' third year. 9M in the year following that for both. I expect 3DS to follow PSPs sales pattern from now on more or less, maybe still being a bit faster in it's lifecycle (and so losing overall a bit more sales).

The drop was as nasty for PSP, but you're right a year later. I think 3DS is similar in sales pattern, only faster through the life-cycle.