You wrote: "Forcing producers to provide 5(?)-years updates will make prices rise"...
I don't think so: it will oblige makers to standardize processes and software across phones... i.e. very basic specific drivers, then same OS and libs on all phones (with just different themes).
Then the Android security updates can be uploaded directly from Google at no cost. Just like for computers, and phones are computers with very few different features (input device, GSM chip).
My HP or Dell computer is not more expensive when Microsoft or Debian is pushing security updates.
In the end, unifying processes and software brings costs down.
I almost loved this idea on the first sight, but on the second I'm not sure I see how it can work. Will you mandate Apple to make iOS installable on Huawei's devices? If not, why? If yes, how? Who will bear responsibility if SailfishOS won't run on Samsung's hardware? Do you really think API standard can be enshrined in the law, and how you plan to make it safe from corporate abuse?
Btw, if Microsoft is pushing security updates you did pay additional cost for license. If it's Debian then quite possibly you still paid something to MS (if your computer was bought with OEM version), or in better case other corporations, and individuals pay for it (mostly to reduce Microsoft's power).
I don't think so: it will oblige makers to standardize processes and software across phones... i.e. very basic specific drivers, then same OS and libs on all phones (with just different themes).
Then the Android security updates can be uploaded directly from Google at no cost. Just like for computers, and phones are computers with very few different features (input device, GSM chip).
My HP or Dell computer is not more expensive when Microsoft or Debian is pushing security updates.
In the end, unifying processes and software brings costs down.