Wikipedia:Don't declare ultimatums
Whether on-wiki or off, whether generally speaking or relating to a specific issue, users should never declare ultimatums. Specifically don't make them in cases where the execution of the ultimatum will result in wheel wars or edit wars. There are no vested editors on Wikipedia, no user has authority over others, so ultimatums only serve to escalate problems and harbor a hostile atmosphere. This drives away new and regular contributors. Even administrators are only allowed to use their tools in very clear situations or when serious violations of policy occur.
Besides never declaring ultimatums, don't even think about them. Just don't decide to take unilateral action before something happens. Use talk pages first, they are there to avoid problems.