Will this current Legendary system last?
We've had gym reworks before and we know the raid bosses will most likely be periodically changed for different types. Does anyone think this will really be the only way to ever catch Legendaries in the game or anyone think they may become available for hatching or at least in lower level raids that would give more people a chance? Personally, I think potentially-soloable raid boss legendaries would be an excellent challenge for high level players and a whole lot more satisfying than taking down a pumped up Arcanine.
Answers
As a random encounter, it needs to be a very low rate of appearance. That´s why they´re legendaries. I think the rate of legendary raids spawning will also decrease by the end of the Go Fest bonuses. But the legendary raid sistem will keep working this way. It´s also good for Niantic, cause it will probably force people to buy premium passes, so... don´t think they´ll change this.