I don't know if Dune would be the best example. Have the producers said that they plan on using the year delay to continue making real changes to the movie? My impression was that Dune was essentially ready to go this year, and doing a re-edit to take advantage of TV's lack of time constraint isn't necessarily ideal or feasible. I agree that Dune as a book has enough content for a TV miniseries. But if they barely finished shooting before covid shut things down, it's not as if they can in early 2021 attempt expand the scope of the story they hoped to tell.
I would argue the "Snyder cut" of Justice League might be a better example, but that's also an extremely weird and bespoke situation. That is actually being released as a 4-episode mini-series. Even though HBO has budgeted $70M for additional shooting and production, presumably most of the cut will use what Snyder shot back in 2017. I'm unclear how much he shot back then was then cut when Joss Whedon took over. Snyder being who he is probably had wanted to do a 3+ hour movie for the original release, and may have actually shot most of those scenes.
I would argue the "Snyder cut" of Justice League might be a better example, but that's also an extremely weird and bespoke situation. That is actually being released as a 4-episode mini-series. Even though HBO has budgeted $70M for additional shooting and production, presumably most of the cut will use what Snyder shot back in 2017. I'm unclear how much he shot back then was then cut when Joss Whedon took over. Snyder being who he is probably had wanted to do a 3+ hour movie for the original release, and may have actually shot most of those scenes.