It’s not about cost to develop. It’s about marketing and protecting sales for other product lines and brands that the parent company (Amazon) owns. There is zero financial reasons for Amazon to give something away via free enhancements to a product that is already outdated technology.
This is why when XT-2 was release, The original XT and all accessories related to XT magically were no longer for sale. Now will Blink release a XT-3 or a different all together product? Who knows.
What I do know is Amazon wont give it away. I’ve asked multiple times on here…how much would you pay for that added feature/benefit that’s on your wishlist/proposal? So far the answer every single time has been a big fat ZERO. People want upgrades but are not willing to pay for them. So knowing Blink customers are cheapskates (like me) they throw their customers a bone with a mobile app update.
Sadly, most of those updates are tweeks to get a product Blink sold to work consistently and correctly. They are typically not feature/benefit updates. But every now and then they are.