Just using the first 160 bits of a new hash function was proposed at one point, but it's not part of the current plan. The new plan is to introduce full SHA3-256 hashes (which are 256 bits in size). More information here: https://docs.google.com/document/d/18hYAQCTsDgaFUo-VJGhT0Uqy...

(Of course, CLI and frontend tools could still truncate display output to 40 hex characters, but internally full size hashes will be used.)