Re: "When it comes to Google, I'm more worried that they might just arbitrarily mothball something on a management roadmap whim."

Spot on. I would that if a site / application is hitting Maps' paid tier they can (somehow) monitize that traffic and cover the cost.

But monitization can't help you if / when they pull the plug.

p.s. I sometimes wonder how often Google looks at Slack and regrets mothballing Wave.