We can ignore this of course. Though, what is the alternative? Stick to Python-based server-side rendering and move in the opposite direction of everybody else? Maintain our own JS stack with 3-5 devs and compete with frameworks that have 10k devs? Stick with the outdated JS stack of Mockup?
We can start to mix in React components, modernize Mockup, etc. Though, where are the developers that are willing to work on this? We asked around to find people that are willing to work on this. We offered to factor out Volto components to be integrated into classic Plone. Though, the truth is I do not know a single developer who tasted a full-fledged modern JS solution and wants to go back to Python-based rendering or mix Python with React.
Just to be 100% clear: The current roadmap does not say that we will deprecated the classic Plone UI. It will still be around as long as people want to use it. You can continue to use Plone 6 the way you use Plone 5.2.
This planned roadmap does not take anything away from anybody. You can use classic Plone, you can use Angular SDK, Vue, whatever you like. As always, we try to make everybody happy.
Volto is something that you can use or something that you can ignore if you want.
The React stack has proven to be very stable and mature in the last years. They rewrote the thing from the scratch from React 15 to 16. We upgraded Volto in half a day. They kept their router implementation stable over years, when Angular replaced their router 4 times from alpha to rc. This is all very impressive if you dare to look at it.
I'd personally rather bet on the future and maturity of React than on the future of Plone or Python in web development. Though, of course nobody can predict the future.
Volto is a major selling point in my experience. I wouldn't know how to sell my clients an expensive Python 3 upgrade without a real gain like Volto. With Python 3 and Volto I can provide our clients with a future proof, stable, mature, and secure backend and a future proof and modern frontend.
This is one of the great stories about the Plone community. Two groups of developers worked their asses off on unrelated areas (Python 3, Modern JS) and with Plone 6 those efforts come together to ship a mature, stable and future proof stack.