If you're a corporate customer, then you take that risk when you sign up for a month to month contract. Now usually a month to month works very well for you, but it is a risk you accept.

A lot of corporate customers will seek longer term contracts, a year or even longer, so they can lock in a price and various service guarantees. Even in the case of this acquisition it's only customers on a month to month plan that have to migrate by September, customers on a long term contract will continue to have access and support for the duration of their contract.