Closure date to vote on a proposal
Existence of an option to automatically extend the closing date of a vote, while a minimum participation of group members is not achieved.
We have discussed quorums in the past (such as this thread).
I think this is an example of a process which can easily be done manually, but is much more convenient if automated. So, it's a good idea, but maybe not the first development priority.
Then, be necessary to wait
That's a very interesting idea. I do believe strongly in having quorums: requiring a minimum number of participants, in order for decisions to hold group-wide legitimacy. (I also believe that it's important to allow all members a reasonable amount of time to engage in a discussion, regardless of whether or not the quorum has already been achieved.)