Yes, that is true. They are down to one concourse at CVG and it's maybe 1/3 of a mile long. I very much doubt they would close the door at the 15 minute mark if they are still waiting for connecting passengers. I routinely see late arriving passengers boarding at the 5 minute mark for international flights.
And MCO-CVG is one of the few mainline flights left, and most of the mainline flights at CVG use the western half of the concourse (the low numbers; B-1 through B12, usually), while the regional jets use the eastern half of B. Shouldn't be more than 2-3 minutes to walk from arrival gate to the CDG departure gate.
That said, OP, if your MCO-CVG flight is looking like it's going to be delayed at all, start working altneratives at the check-in counter or with the gate agent in MCO ASAP (either via ATL, JFK, DTW, etc.) - it wouldn't hurt to have a few alternatives in mind, in fact, as I've found the best success with gate agents and getting rebooked is asking them for something specific that you know already works (pending available seats).