I don't think it would be hard to convert to sci-fi. To me the basic Frostgrave game engine is very simple and easily adaptable. You might want to tinker a bit with different shooting weapons and decide how much and what magic is involved. A lot of the spells could be explained with some sort of tech equipment and the skills would work as is if renamed. For example arcane lore and read runes made into computer programming/alien languages or something like that.
I've really liked Frostgrave ever since it came out but prefer magic as a supporting element more than the main focus and I've always liked the idea of the henchmen leveling up. So Shadowdeep is ticking all the right boxes for me and my kids right now. The only thing I'm thinking of house ruling for us is maybe allowing the henchmen to pick different weapons or armour as one of their level ups. And importing creatures from Frostgrave, Ghost Archipelago or other games once I start having to design my own missions.