A few years ago, it was realized that using number generating RSA keyfobs for authentication into VPNs was not a completely secure mechanism. Some companies that previously relied on RSA for this have migrated to using SmartCards with PINs instead. Combining this with enterprise products such as Citrix Receiver have worked pretty well so far.
With the release of OS X Yosemite, Citrix no longer works with SmartCard authentication. Both Apple and Citrix have acknowledged this, but according to the forums on those sites, it doesn't seem like a heck of a lot is happening to resolve the situation. As a result, people who use Macs at home to remote desktop to their office are unable to upgrade to Yosemite since it means that they'd no longer be able to work from home.
I'm curious if anyone has any idea or insight as to what exactly changed with Yosemite and why would it be taking so long for either Apple or Citrix to come up with a fix? You would get the impression that either Apple has completely broken the support and just doesn't care or Citrix can't get an engineer to make some tweaks.
Any idea as to what exactly was the breaking change and perhaps why would this be such a difficult problem to fix?