The Sentinel migration mental model question: what's actually retiring vs what isn't?

I went ahead and wrote up the full breakdown based on the framing above. If it's useful for anyone working through this: https://securingm365.com/defenderxdr/sentinel/sentineldefender-part1/

Covers the architectural distinction in more detail, the operational changes that actually affect day-to-day SOC workflows, and how to think about the planning horizon given the extended deadline. Written with the scale and multi-tenant crowd in mind rather than single-tenant simple environments.

Would genuinely welcome any pushback or edge cases people have hit that aren't in there.