I’ll admit it’s definitely weird, and seems sketchy, but it says right there at the end, “If you don’t return this card… yada yada yada… next time you vote.”

So if you don’t receive or overlook this letter, then “next time you vote” they’ll just have you do what they’re asking you to do now. I don’t see anybody getting disenfranchised, here. I just see standard bureaucratic paperwork.