The idea that third-party solutions will fix 0-conf... it completely throws the baby out with the bathwater.  Sure, it could work -- Visa works.

But it would no longer be bitcoin.  It would no longer be a global peer-to-peer currency.

There is a third option, aside from third party involvement and shorter block times.  The third option is innovation in the bitcoin consensus system itself.  Economic incentives keep miners following the rules today.  It may be possible to add incentives that lead to 0-conf transactions being very reliable in practice, on a time scale much shorter than 10 minutes.