That's a great idea. It reminds me of better version of a feature my Super Strada has. If you look closely at the chromed part of the seat stay, you can just see the peg:



It's designed to accomplish a similar task. Basically, you shift to the highest gear, then pull the chain up and drape it over the peg. It's a great feature I wonder why more frames don't have it.

The Portacatena design would be and awesome addition to current racing bikes. Instead of going to 11 speed, they could just keep the 10s spacing on the cassette, but make the non-drive side of rear hubs narrower to accommodate.