I have a bias here but I don't think its ok. They should put me on another flight & not ask me to just wait to see if something opens up. I bought the tickets over 6 months ago when I had a number of other choices. All those choices are now gone.

I've been in multiple scenarios with Delta where the operating carrier was another Skyteam partner & they cancelled or changed a flight. DL has always put me on another flight & not asked me to wait & hope that everything works out.