In reply to Stephen Vaughan.

Yes, most likely that jQuery code will need to be updated. There is some time left before this is necessary, and the core team will likely be looking at numbers of themes/plugins that have updated their code and listening to feedback before they move forward with Stage 2 and 3. That's why those are tentative dates at the moment.

But, yes, definitely be looking for updated code if you've added it yourself to the child theme or talk to the child theme author if they added it.