Clearly if your collaborating on acrobat project and your on Mac platform and you corporate customer is on PC with newer version, you may be screwed if you can't get full functionality. MSFT did it to APPL on Office for Mac several years ago.
hmm. well, i think you're still overlooking (1) the fierce loyalty of mac users who still can't get used to the braindead complexity of windows (even xp); (2) the fact that many of the shops you're talking about will be homogeneously mac or windows (cheaper that way), or if large enough for variety, will have even some primitive sort of workflow management - meaning that the artists can use whatever they want, the editors whatever they want (hey, doesn't framemaker still exist?), etc. and someone will be in charge of integrating and producing the final output; (3)
MSFT did it to APPL on Office for Mac several years ago.
yah, although msft also did similar to corel, borland etc (now, msft in apple's shoes, releasing competitive, "free-er", integrated apps competiting with others. e.g. how many times do you go to a site and find that what they're presenting is available only in quicktime? doesn't mean you'll turn around and leave.
anyway, in sum, adobe would be foolish not to pursue the mac platform, cuz if they don't they'll alienate a big chunk of their user base. no way is adobe going to be able to force migration of users from mac to windows. if all of the incentives so far haven't done it, this won't be the turning point.