See latest Cloudera announcement about moving to a subscription model.

https://www.cloudera.com/downloads/paywall-expansion.html

Does this mean that even the older versions (6.3.x and older) that until now have still been available for download without a subscription, will no longer be available without a subscription?

Does that mean that if you have a cluster running 6.3.x without a subscription, you can no longer add new nodes to the cluster? or might this still work if you have already downloaded the parcels using Cloudera Manager?

What is the status of making all the code (such as Cloudera Manager) open source and available?

I've not seen any news about that anymore.

The pricing for CDH is very high, probably a lot of "legacy" users cannot afford it, what is the best option if you now need to move away from CDH, use plain Apache Hadoop? or other database such as Clickhouse or AWS Athena?

i appreciate any info on my question.

Lot's of questions.