Answering some questions here…
CRUD changes in Glide Tables and Glide Big Tables no longer count as updates. That was a significant change for teams working with large volumes of data. What count as updates now are more resource intensive, like syncing with external data sources. The tweaked plans should reflect that.
Cancel your subscription and resubscribe to the new Maker plan. The same is true for the Legacy Business plan. Just cancel and resubscribe to the new plan.
You won’t need to rebuild your apps. 
It’s a hard limit for the Maker plan. If you need more rows, you can upgrade to a Business plan or contact our sales team for a custom quote. 
We’re not touching Legacy plans, but if that changes, we’ll give plenty of advanced notice. The team’s been very mindful – and diligent – about not moving longtime customers off their plans unless absolutely necessary.