Obviously, a Bluetooth certification doesn't mean that the device will get an update next week, as that's not usually the case. What's more, it's not impossible that while this particular certificate is now checked off the list, the company still has quite some work to do on Lollipo -- despite having had access to the developer preview (Android L) for months now. That, at least, is how it typically goes -- the more significant the custom skin is, the more time it takes for OEMs to debug it and ensure that it'll be problem-free enough for prime time. What's more, do keep in mind that if you're on, say, AT&T or Verizon (or any carrier on the planet, for that matter), the Lollipop-touting One M8 will still need to pass through your provider's own certification. Unfortunately, that procedure can usually take a while, so it's definitely possible for Lollipop to take more than 3 months to get on your device.
HTC promised that the One mini and One mini 2 will also get the 5.0 release, but didn't burden itself with any more specifics. It's likely the case that the minis will have to wait longer for Lollipop. We'll keep you updated as we go through the end remainder of the year.