Here is another way to phrase what I am proposing.
You can think of BTSX as an altcoin that was allocated 50% to an AGS snapshot and 50% to a PTS snapshot. It changed the social consensus in that future forks of the BitShares X DAC are expected to snapshot BTSX rather than AGS/PTS (and that is perfectly acceptable to our community).
Similarly, you can think of PROTO as an altcoin that is allocated 50% to AGS, (50-x)% to a PTS snapshot, and x% to the creators of the coin. The value of x will likely be very small (x < 1%?) and just enough to cover the fees involved for this process. This coin is guaranteed to never have any inflation. PROTO, like BTSX, also changes the social consensus. Instead of crediting at least 10% to AGS and 10% to PTS to get the support of the BitShares community, now DAC creators need to credit at least 20% to PROTO holders to get the same support.
Just like how the snapshot of PTS for BTSX caused a massive drop in price of PTS, the PROTO snapshot will cause a massive drop in the price of PTS. PTS will still exist after the snapshot, but because of the severe change in the social consensus, we expect its price to drop 100% down to zero. This means it makes no sense anymore to keep mining it, and it makes no sense anymore for exchanges to list them for trading.
Just like any other DAC snapshot, we need to give everyone clear notice about when the snapshot will occur and make it clear to everyone that it means that the price of PTS will drop to zero after the snapshot. And of course, this all requires getting the broad support of the community in agreeing to this change in the social consensus. Also, to reduce trading downtime, we should choose the snapshot date to be at a point in time when we are actually ready to quickly transition over to the PROTO asset on the BitShares X blockchain.