... I have been told by a leading industry figure with an immense amount of expertise and experience that it is perfectly possible to support TDM in a 64 bit version of Pro Tools.
It's prolly true - I mean, with software, you can almost always throw more work at it to make it do what you want, right?
But it's probably a ton of work...
I mean to start with, RTAS and
TDM plug-ins are 32-bit, right? So they're not going to run inside a 64-bit app on their own accord. ('member TDM plug-ins have a piece that runs the UI inside ProTools, and a piece that runs on the TDM cards - the UI piece is 32-bit) So right there you've got a huge obstacle. Now you could do something clever like make a special separate 32-bit app to run the plug-ins and talk to the TDM cards, while the main Pro Tools is 64-bit and it could find some way to talk to that 32-bit plug-in running app. It kinda sounds like a hack, a lot of work, and you still don't get the benefits of running 64-bit plug-ins.
Or they could revise the ancient TDM / RTAS plug-in formats to support 64-bit, and try to convince all the plug-in companies to do a bunch of work to 64-bit-upgrade all these TDM plug-ins that run on hardware that isn't even made anymore. The plug-in makers probably wouldn't sell many new copies of those 64-bit TDM plug-ins to pay for their effort - just upgrades, which we'd want for free in any case. Seems like a tough sell there. Why not spend that effort bringing the plug-ins to the new format?
Anyway, may be off on the technical details - just sayin' it sounds like it ain't worth it, though it would surely be convenient for us.