As far as I understand it they're actually underwater on their API and even $20/month pricing, so we'll either see prices aggressively increase and or additional revenue streams like ads or product placement in results.
We've witnessed that every time a company's valuation is impossibly high: They do anything they can to improve outlook in an attempt to meet it. We're currently in the equivalent of Netflix's golden era where the service was great, and they could do no wrong.
Personally I'll happily use it as long as I came, but I know it is a matter of "when" not "if" it all starts to go downhill.