Can't say I'm surprised that the ending leaves sequel possibilities open. If LoS2 does sorta-gangbusters like the first game, it'll likely stick around for a while as Konami finds other developers to make more LoS games on the cheap.
I agree with Enric that the next game should be completely different. If LoS did anything right, it was proving that the series can shake things up and still be successful. Although the lesson Konami will take away from it will likely be "DAAAAAH IT SOLD A LOT LET'S MAKE 15 MORE, BAWS".