I may be wrong, but this isn't a reboot/remake: it's a sequel that is passing the jobs onto new people (in this case, women).
There was a .01% chance that Ghostbusters 3 was going to happen with the original cast. Akroyd had a script and could never get Murray to read it. Now with Ramis passed away, any chance of the original cast reassembling is gone.
Last I heard, the next idea was to have at least Akroyd appear in the new one and selling the franchise rights to the new cast. The idea of Ghostbusters being a franchise for sale was mentioned in the original. There were rumors of Seth Rogen, Paul Rudd, James Franco and others being considered.
I'm not commenting on if the female cast is a good idea, just that I don't think this is meant to be a remake or reboot; they aren't dismissing the original continuity, just bringing in a new cast.