You still need to maintain that sandbox. Ultimately no one wants to spend energy maintaining software that isn't used very heavily. That's why feature depreciation happens. If someone cares enough, they should step in an offer to take over long term maintenance and fix the problems. Ideally a group of people, and perhaps more ideally, a group with some financial backing (eg a company), otherwise it may be difficult to actually trust that they will live up to the commitment.

Even projects like Linux deprecate old underused features all the time. At least the Internet has real metrics about API usage which allows for making informed decisions. Folks describing how they are part of that small fraction of users doesn't really change the data. What's also interesting is that a very similar group of people seem to lament about how it's impossible to write a new browser these days because there are too many features to support.