It seems there will be a free "community edition" which is limited to the PICkit 3 and simulator, and a full version you can buy.
I would hope that would also work with the Microstick and development board debuggers, as they are essentially Pickit 3 units built into them. Microchip would be stupid not to include all these.
Interesting the way the web page is laid out - one wonders if Microchip are going to replace all their web pages with this format. It looks like someone has finally figured that the software development team needs their hands tied behind their back, and stopped their funding to go out and use established packages.
Arriba really does look like it is going to be the death knell of MPLAB-X as we know it.