Yeah, it's odd considering Marco already produces very nice Kindle articles out of Instapaper, so he's familiar with the format. And Kindle supports subscriptions.

In The Magazine FAQ Marco says he's looking at the options for Kindle. I'd be surprised if there's not a plan towards having it given Marco seems to be a very big fan of the e-ink Kindles.

That would be very nice.

I primarily read Instapaper (Marco's more well-known creation) on my Kindle rather than my tablets or phone.

For all of the integration between Instapaper and Kindle, I think that it's a possibility.