Thank you for sharing with us that you don't actually know how energy-based classes work. No energy class is ever GCD capped, for a simple reason: abilities cost either energy, combo points or both.
20% haste increases our chi generation by 20%. If hasteless chi generation is 4 chi every 10 seconds, that's 26 chi per minute. Thus, every 10% haste adds 2.6 chi per minute to our rotation. Chi burst adds 2 to 4. WDP is resourceless, so it's "worth" at least 2.8 chi per minute.
So if the base is 26 chi per minute, with 20% haste and mentioned talents it becomes 36. With Energizing Elixir counted in, it's actually close to double of "regular" chi generation.
Since all of our real damage abilities cost Chi, as a WW in BFA today, you sooner run out of abilities to maintain Combo strikes than out of Chi, because the only spammable ability besides Blackout Kick is Tiger Palm, and you're either short on energy or on chi, extremely rarely on both.
There are, however, two styles of rotation (four if you count AoE): one is for burst, one is for maintain. If you go burst, yes, you'll run out of resources, especially if you don't talent Energizing Elixir. But this style is best suited for dungeons where there's plenty of downtime. Current situations where a tank grabs half the instance in one pull is going away literally tomorrow on wednesday when raids open. It's not very energy friendly because you're trying to both burst and maintain, which is impossible. If you use the "maintain" rotation with mentioned talents, the above statement is true - you'll almost never run out of buttons to push.