One thing to be learned and understood at many levels of employment, even CEO, is that when you think you are bigger than ownership you have just stepped on the banana peel. Exact wrong time this year to be talking an extension when DD's contract covered 2020 already. Results count in every business except politics and utility companies where f***wits prevail over decades of ineptitude. If DD said it's me or the door, he committed a form of professional Hari-kiri. One thing I know about working with "billionaires" is that you are not them, you are not "family", you are the well compensated help, and don't forget it.
DD being gone will actually make some of the decision making that was needed about personnel in 2020/2021 a bit easier because it will have been all his "fault". Now the next up to GM will have to deal with the Betts dilemma, Sale and Price's issues, JDM's 2 walk years and rebuilding the farm while remaining relevant in the AL East. That person or committee (please, no) will be well tested by the Dombrowski debris field. Dave might sit out a year, collect his money and sooner or laterr a hungry owner who thinks Dave can get him into the WS will capitulate and say can you do it here? Dave will say, show me your farm system rosters, I think I can help.