I see where you're all coming from but I guess I think differently.
I'm only starting to look at other options from BES to cover for the possibility of RIM failure. So, I'm not 100% sure of these comments.
I can't imagine not using an MDM solution to get the same (or almost) control BES gives. For most of my users that is block everything except phone, text, BBM and email. Yes, I'm mean that way.
And, I'm not sure BYOD would be less support as a good percentage of my users have difficulty changing their passwords when BES forces it. The thought of certain of my people trying to use Android or iOS sends me into fits.