Iunno about if it had been released free-to-play, if it would have done well enough to survive the grind. No offense, but there were better MOBAs before and after it that still got blown away because of reasons.
That said, what foresight you guys had back then really could be used for games nowadays. Even with it dead, I can still play it and have fun with it, which I can't do with several games I enjoyed. And do minor modifications as well.
That said....If...If I or anyone else could do major modifications-- edit maps, add new heroes, abilities, and code-- the game could be revived. That's the critical point there; Unlike most of it's peers, Demigod can be brought back. It's a distinction for most games, on whether or not they're a passing fancy or a long term community. Look at Valve games; look at your own older games with mods; Look at the difference between SPAZ 1 and SPAZ 2. Heck, look at the difference between Terraria and Starbound. Terraria, for all it's polish and enjoyment you can get out of it, will one day no longer be sustainable community wise, simply because modding was an afterthought. Starbound, will live along the lines Minecraft did; Kept alive by those who know how to code and those who desire to make more.
To that end, if you do make a squeal, please take my advice to heart. Your first two major priorities, coding wise, are to make it custom server, Peer-to-Peer based like you did with Demigod, and to make it FULLY moddable. Adding in adjustable bots as well will be a key step as well.
For all of my dislike of Awesomenauts and personal and professional disgust of Ronimo, the one thing they did right was to first make it P2P based, and thus sustained by those who WANT to play, rather than sustained by paid for servers. The other thing they did right, was to allow the playerbase in on the development process, second and then first hand. Even if I dislike the game, I know there's people who love it, and will keep it alive for years or even decades to come, simply from those facts.
Same applies to Dungeon Defenders, which I just got back into. Again, P2P connections means even if the company vanishes, the game won't. And not only do they encourage and help modding, they now have a dedicated modding community directly involved in official patches and hotfixes.
Learn from that. You guys have shown you can do really good works, when you try.