Someone else already pointed it out but they're not really switching engines DNF style. Lumberyard is a fork of CryEngine and is more or less the same thing. They're likely making that switch because Crytek is all but dead at this point. The reason Crytek didn't go under the last time they had money problems is because Amazon paid them $75M to basically buy CryEngine outright, everything except the actual copyrights. That's why CryEngine is actually free now, except for premium support, because Amazon made Lumberyard free.
The reason CIG is switching to this is likely because Crytek is all but dead now. They just closed all but 2 of their studios, after months of payroll issues. Crytek took the money Amazon gave them and blew it making VR games. VR games that no one bought because so few people have bought headsets that it's almost impossible to make money on VR games unless a headset maker bankrolls it for you.
I have little faith in Star Citizen but all this took me 5 minutes to figure out. Of course, proper research is too much to ask of the gaming press these days, especially when it's easy to generate clicks with a controversial headline. Bottom line though is that CIG isn't really switching engines, they're just switching to the Amazon version of it because Crytek will probably be bankrupt within a few months.