It would be nice to have a mode that would have a more long term style with saveing and reloading. That would bring in the people who want a long survival game while keeping the origanal game mode for everyone who wants that. Otherwize, once someone beats the game they would just become disiterested with the game. I would also be fine if you added it to after you escape through the jump gate. This then would be a game that I would sink a year into while still having tons of fun.
I love the idea of a long-term survival mode too. It's a fantastic idea and one that I seriously considered during the design phase.
There's plenty more planned than what you see now though. Beating the first boss will not be the end. It's just the beginning. It simply the first goal for the player and the section of the game that I'm focused on tuning and polishing during this free alpha version.
Many more bosses, secret bosses, more enemies, and dozens more planets with their own challenges are still to come.