Let’s park that. — We will set this point aside and come back to it later.
Let’s put a pin in it. — We will mark this point so that we do not forget it, and return to it later.
Hold that thought. — Please keep your point until the right moment.
I don’t want to go down a rabbit hole. — This topic could take a long time and lead us away from the agenda.
That’s out of scope for today. — It is a fair point, but it is not part of this meeting.
That deserves its own meeting. — The point matters too much to handle quickly here.