It looks like Netflix will host a shorter version of Monday Night Raw when the WWE program debuts on the streamer in January. The WWE has not officially announced that the show will remain at 2 hours after announcing a shorter run time going forward on USA Network, but considering the nature of Netflix, being a streaming platform with multiple tiers of ad-free viewing, there is less need for advertising real estate.
Netflix does have ad-supported tiers in its intro level pricing and like Amazon, will soon convert the lowest tier of its service to a commercial-based option. It is possible that if Netflix gains customers specifically for access to the pro-wrestling program that they will be open to advertising as they have always had advertisements associated with the show.
As for whether it will in fact remain at 2 hours it will depend on the numbers once Raw lands on Netflix. 2 hours of content with limited commercial interruption looks a lot different than 2 hours of content with the frequency of ad breaks viewers get on a basic cable channel like USA Network.