Worst... I guess we'll have no choice but to impose entry restrictions. Something like distributing numbered tickets.
Literal
Worst... entry-restriction [object-を] set-up [only-しかない] [polite-でしょう]. Numbered-tickets [attributive-の] distribution [or-something-とかで].
Event planner's dismayed muttering. 最悪 ('the worst') used interjectively means 'this is awful, the worst.' ~しかない ('no choice but X') is a common idiomatic pattern combining しか (only) + ない (negative) after a plain-form verb. 整理券 ('numbered ticket for queuing') is used at popular events to assign entry order. とかで ('something like, with X or the like') lists a vague suggestion. The trailing 体言止め adds a weary afterthought.