Most org structures have this sort of decision escalation process built in, even if it's not explicit. If a team fails to arrive at a decision, their boss should step in to pick a direction.
This is one of the many hidden problems in flat org structures: Without an obvious person to break up disagreements and point teams in the same direction, you end up with small groups of people working in different directions or even working against each other. In practice, someone like the CEO usually steps in and overrules these messes, but it's not efficient to have to escalate all the way to the CEO.
It's also important to build teams that can disagree but commit to decisions they don't particularly like. At some point, it's more important that the teams work together on anything rather than debate endlessly.
This is one of the many hidden problems in flat org structures: Without an obvious person to break up disagreements and point teams in the same direction, you end up with small groups of people working in different directions or even working against each other. In practice, someone like the CEO usually steps in and overrules these messes, but it's not efficient to have to escalate all the way to the CEO.
It's also important to build teams that can disagree but commit to decisions they don't particularly like. At some point, it's more important that the teams work together on anything rather than debate endlessly.