Keeping up with web standards, and dropping the advertising rubbish that's making them somehow atrophy users faster than they were before.
Otherwise, they'll be gone. Thunderbird has proven people are willing to donate millions if they know their money will go directly to the software. In 2022, Thunderbird collected ~6 million in donations (~20 million users) compared to Mozilla's ~9 million (from >200 million users)
Mozilla made $826.6M in 2024. If they got thunderbird levels of support $6/20 firefox would bring in $60 million. Aka 7% of current revenue. Idk all their revenue sources so idk what the overall picture would be, but my gut says $60mil wouldn’t cut it and firefox will never get the support thunderbird gets because of different user bases.
Eh... I'm not too sure about Thunderbird. For example on Android, they bought a very good product (K-9 Mail), rebranded it to Thunderbird and then proceeded to break every feature which made it stand apart.
Otherwise, they'll be gone. Thunderbird has proven people are willing to donate millions if they know their money will go directly to the software. In 2022, Thunderbird collected ~6 million in donations (~20 million users) compared to Mozilla's ~9 million (from >200 million users)