We're about to launch a new Drupal 8 website for a client, as not all areas of the current website will be on the new platform, and due to apparent legacy complications, the decision has been made to go with the launch on a subdomian (new.clientwebsite.com) with the old Drupal 7 site staying on (www.clientwebsite.com).
The new platform has a different taxonomy and URL structure so We will, of course, be setting up 301's. My worry is that all new content will be indexed against a subdomain, which is only temporary and eventually will be phased out.
What, in your opinion would be the best option?
Should we block indexing of the new site (using Robots) which isn't ideal as the phasing out could take some time?
Any help or suggestions greatly appreciated.