"along with the rest of us" at the end of a sentence
The main point is to communicate your intended meaning as unambiguously as possible. In this case, inserting the comma is what is needed to achieve that objective:
They will have to adapt to it, along with the rest of us.
The comma does not make it incorrect: there is no 'rule' that makes it impermissible to use a comma to mark off a dependent clause. In any case, the requirements of clarity trump all so-called 'rules'.