Starting 20th of June this year (so 3 days ago) every new phone released in European Union will need to have software updates for at least 5 years from the date of the end of placement on the market. This might be the first one released under new regulations. Also looking at Fairphone's history it looks like they really support their phones for a long time.
This is why using SOCs with poor support and closed drivers like this is a terrible idea.
This is software, not hardware. It is ridiculous to pretend it is ok for a phone to artificially stop being useful after just 5 years simply because the vendor won't give software support or even provide the necessary documentation, source code and keys for the community to do.
At least this is 5 years from "the end of placement on the market". So more realistically it should be around 7 years from release.