Windows based PC's would have to be the worst choice you could make for a realtime controller, think about things like plug'n'play, GUI windows/gadgets, multitasking, video, sound and more besides. That the PP driver works as well as it does impresses the hell out of me no matter how many bits it uses. Also the fact that there appears to be no competeion to M3 for PC's suggests that Art's work is extremely clever.
If you went to buy a controller, say Fanuc or Seimens for $10k or whatever, would you expect to find it can also 'surf', play games etc, HELL NO!! Multi horsepower spindles spinning thousands of rpm backed by horsepower level axis servos worth $100k plus all going west because the missus skypes you to get some milk on the way home.
I am not so certain that 32bit and PP are near death either. I have just bought a single board computer, Atom based. There is loads of them out there in all manner of configurations and to rugged industrial spec. Have yet to receive it so may have bought a load of trouble, using Windows 7 Embedded Standard (32bit at my option).
I have every reason to believe these devices and software products will be around for a long time to come
I have spent $8k building my machine and hundreds of hours machining cast iron etc. Why would I not spend $1k and some time to make a suitable controller and protect myself against injury first off and my investment secondly?
Whinging about '64bit support', particularly given the SS solution, seems to ignore the real fact I/we can indulge in innovative CNC for cheap as chips. I was not so 20 years ago, even 10 years. I say go Art and collaborators/community and devil take the whingers!