The series IS as good as dead already. LoS isn't part of the series, it's some kind of Euromix. People fall in love with Euromixes and party the night away, but once the drugs wear off it's just a bunch of repetitive, uninspiring crap. ... Yes, I'm talking about music in the same breath.
When a game series is no longer a challenge to ANYONE, it can be considered dead. The metroidvanias lacked any challenge (until OoE came along, but even that's pretty easy on the whole) andnow it's progressed to just being games of tedium.
You don't see Capcom making Ghosts'n'Goblins in 3D. It's still 2D and still as fucking difficult as it ever was. Capcom and SNK Playmore continue to make 2D games that sell. As much as I dislike either of them, the fact remains they don't simply hop on the bandwagon and grind out Snausages (well, Playmore grinds out Snausages, but they spice it up).
Companies still make 2D fighters. Gamers still buy 2D fighters. Companies make 2D platformers. Gamers still buy 2D platformers. 2D isn't dead and doesn't make a game series dead. Only how it's implemented. I know some people that absolutely love Mario DS even though they've beaten it time and time again. I know some people that love that Mario on the Wii. I know people that will buy a new 2D fighter as soon as it comes out on the market. And I know people that will buy 2D platformers when they come out on the market. The problem is most game companies no longer try to make good 2D platformers.
And if 2D is do dead, why are Maple Story, Trickster Online, Grand Chase, La Tale, and similar games still online and making their companies money? (All of those are 2D MMORPGs.)
... Wait, what the hell was this thread's topic again?