It's impossible to understate just how damn difficult it is to get a movie made. And while it's fair to assume that sequels to successful films are generally easier to bankroll, the sheer number of moving parts involved with any follow-up are absolutely mind-boggling.
From balancing budgets to fitting the shoot around the increasingly successful cast's schedules, figuring out all the legal nonsense, and actually settling on a script everybody's happy with, it's little surprise that so many sequels end up stuck in development hell.
Development hell is the place where creativity goes to die - or rather, fester forever more. It's a place where announced films simply languish in a not-quite-dead state, whereby they haven't been formally cancelled yet it seems incredibly unlikely they'll ever actually get made.
We've of course seen sequels unexpectedly crawl out of the abyss to shockingly impressive effect - Mad Max: Fury Road is perhaps the gold standard for this - but it's sadly far more likely for long-gestating sequels to simply never happen until somebody finally admits they're cancelled.
These 10 films could happen, but you shouldn't bet any money on it...
10. Live Die Repeat & Repeat
Doug Liman's 2014 sci-fi actioner Edge of Tomorrow was a major critical success, yet poor marketing led it to underwhelm at the box office.
Nevertheless, in large part due to the film's strong home video sales, a sequel soon entered pre-production, with Liman signed to return in early 2016 alongside stars Tom Cruise and Emily Blunt.
The sequel, entitled Live Die Repeat and Repeat, was loudly hyped up by an enthusiastic Liman in the years that followed, and though Cruise and Blunt both spoke highly of the sequel's concept, it was ultimately a matter of allowing everyone's schedules to coincide.
By January 2020, despite numerous screenwriters taking a crack at it, Liman said the film was still in the "planning stages," and in 2021 stated that it was basically up to Cruise and Blunt as to whether it got made.
In a May 2021 interview on Howard Stern, Blunt seemed less sure of the sequel's status, noting that it would require a huge budget which, in the current budget-conscious Hollywood climate, wouldn't necessarily be practical.
Then again, given that Cruise is fresh off the biggest commercial success of his entire career with Top Gun: Maverick, Warner Bros. might be pushed to reconsider their stance.
Cruise's schedule has just opened up considerably with him recently wrapping the last two Mission: Impossible films, so while there's probably never been a more likely time for the sequel to happen, it's still not worth getting your hopes up.
Warner Bros. is also developing a spin-off TV series, which without the need to wait for Cruise and Blunt has a much better chance of actually going before cameras.