if there is going to be a hard consensus to move to adaptive /dynamic blocks. then there would not need to be the 1:3 ratio of a block inside a block.

instead at a point where all the nodes are ready to accept adaptive blocks, validating segwit can be part of standard consensus.. meaning it can be just a single block format that allows
(TX input)(sig)(TX output) - native/legacy tx
and
(TX input)(TX output)(sig) - segwit
all in the same block area

thus allowing a CLEAN single merkle block where people that want to use segwit tx's can.. and those who want to remain with native tx's can and then that unites the community because there is no cludge of tier networks of stripping blocks apart and compatibility issues between different nodes.

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also

this would cause orphan risks of when nodes rescan the block chain

if 2016 blocks were X then the next time 2016 blocks were y(=x-0.01)  with the rules being Y.. all the X blocks would get orphaned because the 2016 blocks that are X are above the current Y rule.