> how will I know if they will still be around long enough for me to use it?

Treat it like a donation. I know not all can afford to do this, but many of us can.

You don't! Its a best effort contribution to help improve their probability of surviving this crisis.

*Exceptions: Large Chain Restaurants

Think of it as a crowdfunding campaign for your favorite local businesses - hopefully you'll be able to enjoy the benefits of the money you spent further down the line, but even if you don't, you know you supported someone or something you believed in.