Me neither as that would be rather stupid. But after working on OFP, ArmA1 and ArmA2 it's understandable that they want to do something different now. No problem for me though I probably won't be interested in any fantasy stuff.
I'm pretty sure that after OA they will take a break from military sims but will be back in business one day. Besides that, ArmA2 with OA
(and eventually another addon) will surely keep us busy for years to come, not to mention all the stuff the community will produce.
Take a look at OFP - people still releasing Mods and addons for it after more than 8 years.