Before you start a sequel you should probably finish the quest lines you've started. I'm alright with the main story ending at the Khrono Tomb but please finish up the side quests. I'd also like to see what those games that the mysterious sniper talked about in her Game Over are about.
As for whether or not you should take a break after 0.5.0 that should honestly be decided by you. I can understand feeling burnt out after working on this project for the last two years and if you need to take a break and do something else in the meantime go ahead.
All I ask is that if you make another, probably smaller game in the meanwhile please actually finish it or you may become another indivi. I like their games but they never seem to finish them.