In fact, I believe most modern films—including big-budget blockbusters—are still being mastered in 2K (with UHD Blu-Ray discs being upscaled from the 2K masters). My question to anyone for whom spending $300 on an NLE is a big deal: does your project really need more image resolution than titles like Jurassic World and The Hunger Games? Keep in mind that, in addition to spending the $300 on software, your image processing and storage requirements have now quadrupled.
For a close look at the impact of image resolution on cinema viewing, I highly recommend Steve Yedlin's excellent Resolution Demo [0].