I think this means that you will not be able to purchase perpetual commertial licenses for Qt 6 as you could for version 5; only the subscription option will be provided.
I don't think this is to be interpreted that you won't be able to access the LGPL version without a license; but then again, who knows, maybe they'll stop providing builds? Qt is pushing really hard on commertial licensing lately.
This is correct, but this is a huge change to people who depend on the commercial license. I think this means that you will need a subscription for as long as you're distributing the commercial (i.e., non-LGPL) Qt6 with your application.
Well you can get it for the low price of 4k$ per year per developer, or even as discounted as 8.4k$ for three years by paying a lump sum in advance. As long as you don't distribute devices containing Qt, in which case you (also?) pay per device.
This is horible for security. Imagine a piece of software stops being supported, and the developer doesn't renew their licenses. When a security bug is discovered, the dev is powerless. They can't release a new version, even though they have the source code and could fix the bug.
To clarify: This is for the commercial usage of Qt6, the LGPL version of Qt6 will continue to exist, but you won't be able to buy a perpetual commercial license of Qt6, everything will move to the subscription model.
Someone mentioned JavaFX as an alternative, but was quickly flagged to death. Could someone explain would would be advantages/disadvantages of such a move in 2020? It's been years since I've looked at JavaFX, and I'm not siure how it compares to Qt6, feature- and license-wise.
But not to the open source ones.