What if there isn't a feasible path for expansion and growth? Vimeo already has contracting revenue, it's either in the maturity or decline phase.

Some customers will churn, some will stay, Bending Spoons are the masters of this model so will have made an assumption on how revenue will change across the next 5-10 years+, but I would assume that they aren't forecasting extreme growth, and instead are calculating that net profit can be changed from c$30m to c$139m within existing revenue, so if they can keep revenue at/near current levels without growth, they can end up with a much more profitable business.

Bear in mind that same revenue doesn't necessarily mean the same number of customers - it can also mean raising prices and having less customers. Bending Spoons might estimate that if they double prices, half their customers might leave - this would still be BRILLIANT for profit, as while revenue would stay the same, some costs would half, and thus profit might jump from c$140m to c$250m based on some napkin math!