

From enduser perspective the most visible change would be that all software wouldn’t be hostile to users because with propreitary you have to be very picky to get that.
In the long term we would see that companies could not build walled gardens to block off competition. Contrast Windows & MacOS vs Linux with its different distros, DEs, toolkits etc.
The least difference would be for enterprise because support is expensive either way.
I actually like Jira. I have my own workflow where I fetch my tickets via Emacs to Orgmode and then work from there. Integration is read-only but that is what I need 99% of the time.