Let me just give you some advice from someone who also waited many years for a sequel to their beloved franchise (e.g. Unreal Tournament).
If a company doesn't make a new game after a few years from previous installment and are making billions of dollars in profit. It's time to move on, they don't care.
Can you imagine Nintendo not releasing a new Mario game every 3 months? It would be considered heresy.
Never say never though, we got Shenmue 3 released after 18 years. Even though it kinda was mid and sucked. Didn't sell well at all, so we'll likely never see a Shenmue 4-5 to series completion.