We are still operating independently from Bell since the sale is not finalized. However that is a question a lot of our customers have been curious about. You have access to all the same services and there will be no changes to your billing. I realize your question is asking about the 'unlimited data' after the takeover but as it stands nothing is changing.
For wireless, MTS currently offers the "flat rate" data plan. In the past customers on other carriers have been told they can maintain their legacy (out of market) plans but cannot receive subsidies on new devices which require approved in-market plans. This is pretty normal for most wireless carriers so it will be some level of wait and see with Bell on the wireless side.
On the (wired) broadband side, in other markets Bell currently has data caps. Customers can either accept those data caps and potentially pay over charges or they can purchase a plan upgrade for unlimited data, for I believe $15/month. Without the plan upgrade the cost of the plans is fairly similar to what MTS charges. You can check the Bell site if you want to see what is offered in Ontario.