i think the PRICE would stay stable because the last sold would probably last for ever since no buy/sells can be made.
atleast on coinmarketcap or at brokers.

The VALUE  however would drop dramatically, imagine those who enable adoption with btc-marketplaces and every business model working with btc. nobody would want to enable btc paymets for their value proposition because nobody spend their btc.

Thats the exact opposite then what we need. we need to spend our btc to feed the ecosystem so it can grow.