Doesn't this work in favor of the pricing structure? The future could take however long, so to keep development going it'd be fair for them to be paid again for that at some point.
They're also considering making a lifetime price, and/or to release new versions yearly (possibly using 20xx version numbers, so then you're pretty much just paying for every new version anyways) given this structure enables them to.
I'm really just seeing it as a perpetual license, with 1 year (or 2 years) of updates included. I really wish they never called it a subscription.