If you haven't already sold your ALTs simply hold if your project is decent. If the project has no future sell and buy into a decent project. This is all you can do to recover your loss without putting in more money. It will probably take a couple of years to recover your loss!
Some ALTs will never recover from this crash!
It is an ugly situation!
I don't think some altcoins may recover after it is dumped already. You must have to look at the top coins where there is a possibility to rise, a potential coin that would make a change even when years passes by. Just look at the top 100 coins in the marketcap some of it has the potential to grow even more after a year of crashing.
Fully agree with your statement, it depends on the potential and trustworthiness of the projects / digital currencies.