I think you make a good point on the coins that will sustain during a crash. Personally I think the question it self should be which coins besides the 4 on Coinbase will hold their value. Obviously if coins are on Coinbase they have a huge advantage for that kind of market. So besides those 4 which 5 do you speculate? I think your spot on with Monero and From there personally I would add ADA, XRP, Dash, and XLM.