This move is, in my opinion, a bad read on the odds and European culture.
First, culture. The goal (at least in France, but that's probably the same in other countries) is to get you in compliance, NOT to fine you. What this means is that before you get lawsuit and fines, someone will talk to you and work with you to see how you can get compliant.
Second, the odds. Unless you are a big company that thrives on GDPR violations (doesn't seem to me Instapaper is one, but I could be mistaken as I never used the service), you aren't likely to be targeted before a while, at least until a big case is done and over (let's take the odds Facebook is first).
Third, the delay. While the GDPR takes effect tomorrow, you have a grace period of a year for part of it (for example, getting consent for newsletter). I would really be surprised if enforcement start tomorrow.
Well, at least that's my read on the situation. And that's how I intend to do it: pro-actively work into getting in compliance without rushing it too much, and handle things properly as they come.