At least some small part of this is not a 64 bit issue but a business issue, in that Apple is cutting some codecs they had to pay licensing fees to use, as I understand it.
Keeping some older OS systems and it’s host hardware around is an option, but not as “simple” as it may seem, since, you’re now counting on that machine never breaking down. (And eventually, they will…) …and on there being a replacement for it if it does.
I have a gorgeous $3k iMac in my garden toolshed, stuck on a shelf since the graphics card melted down one day, well after Apple stopped replacing the bad units. I *could* spend as much as the computer was worth to get an OEM replacement, and find someone to put it in… or try to do it myself… but it’s not financially prudent. And that’s going to happen to everybody who keeps an older model in a “Bell Jar” for handling these deprecated codecs. I had one of those here at the office until last month or so, humming happily along, when the IT dept. suddenly and unilaterally ordered them all sent to the boneyard, no reprieves, no exceptions. I lost m FCP-7 and DVDStudio Pro workstation on that day. (sniff) You’ll have the ability to still work with them, until suddenly – you won’t. And I guaran-damn-tee you, it won’t happen at a convenient time.
The opportunist will see in this a chance to make some money; helping people evacuate/transcode their files. Bob Z, if you’re listening, this could be a great side business, setting up a transfer workstation hooked to big storage. Maybe make it a rentable fly-away package you plug into the local system, vacuum everything up and transcode it thru an automated script… move on to the next shop.
I think it might also be a small profit center for some developers writing transcoding tools, but then again, if they have to pay a lot in licensing, they might not be able to break-even.
As I understand it, currently Apple has a transcoding scheme set up in Compressor to help you move your stuff when FCPX or Motion detect a codec on the “endangered list”.