Picasa was a desktop app that didn’t require you to load all photos to google. So you could manage large libraries.

Photos is not the same although has many similar features.

And it is just a question of time until photos get discontinued as well...

Photos requires you allow them to use your data to run their image ML on, so it's not going anywhere it isnt quite what it appears. This was precisely the motivation for shuttering the desktop app.

Seemlessly too.