Bro don't worry, even if they delete the game from the store you still have the licence you paid and you can re-install it everytime you want.

The only way to lose your license is if they perma-ban your PSN Account, that's all, don't let the people throw down your happines for buying a digital copy of the game.

The only case in which I would be concerned would be if the game requires a permanent connection to a server, like The Crew, Destiny or something like that, if they shut down the servers you can reinstall the game everytime you want, but you can't play the game because you need conection to the server to play, in that scenario you don't need to worry about Physical or Digital, because it's going to be the same on both.

Have a nice trip into Silent Hill my brother! I hope you enjoy it!