The interweb thinks there isn't much future for Zimbra if Yahoo gets swallowed by Redmond. I`m not sure.
There are different alternatives apart from the being extinguished during the takeover.
I have no clue how the core developers and the management of Zimbra was reimbursed when they were taken over by Yahoo, however I hope they didn't waste all their money and still have some money left. As they went this far with the company already they must have some good contacts with financial people that can help them get a new company off the ground ArbmiZ or ɐɹqɯız would be good names ;)
They could either go with a fresh start, or Yahoo could be so smart to have the guys perform an MBO.
Or even sell the Zimbra assests again .. even at loss.
If getting the Zimbra organisation out of Yahoo doesn't work why not hire the key developers away from the company effectively rendering it worthless , big chance you don't have to hire them away from their current job but just be waiting at the front doors when the exodus starts, people either don't want to work for the new company or will be forced to leave as they are redundant.
RedHat has a big opportunity here .. they don't have a relevant mail offering yet, there have been rumors around RedHat going to partner with the OpenXchange folks but I haven't heard from that yet .., but other companies might have look at the codebase also.
Would we need a fork ? We don't know yet ..
But I don't think we have to worry that much .. I think there are bigger things to worry about ..