Since you dont understand the system, let me repeat slowly:

a) zero can only be reached if there is no longer sufficient divisibility to allow supply and demand simply take care of that by in a sense DEFLATION. as long as divisibility is assured the practical use of bitcoin will not be affected at all
b) if a trend can, in the far future, be anticipated that there might be a looming issue on the horizon, a fix to that issue, however that fix may be, can be introduced to the mainline client. if that is a "vote on branching" or something different does not matter, the tools to fix it are already there
c) why does every random person who seems to be in the "explore bitcoin phase" set his first and foremost task at solving longterm issues for bitcoin before even grasping basic concepts or the currency