This feels like email all over again. In the early days of email, everyone had their own IMAP server, and it was good. Then spam happened. Slowly it got harder and harder to jump through all the hoops needed to ensure your email was delivered to users of gmail and other large email hosts. Even if you were willing to filter all the spam out from your own inbox, it became practically impossible to get delivered to most other users.
I wonder if we will see something similar happen with browsers now. Cloudflare and other proxies will rely on increasing levels of fingerprinting to sift out scrapers and bots. Already it's not uncommon to get false positives on Linux+Firefox. Maybe if our overlords are feeling particularly benevolent, Firefox might make the cut for browsers allowed to access the vast majority of sites behind CF, but anything smaller will be blocked. Effectively this will kill rolling your own browser.