Sasuke has Rikudou's chakra which will damage him. He regenerated from a Chidori slash. PS slash , especially with the strongest PS in the series, is way more powerful.
Madara still will be able to regenerate .... Strong attack or weak attack doesn't matter to him .... Wasn't 8 Gate Gai a strong attack ?
Even if PS slash was stronger than 8 Gate Gai attack .... Madara will just regenerate
The only way to defeat Madara .... is to seal him . ( Or what BZ did ) .
We don't know what Madara's third eye can do
We don't know what was his MS ability
We don't know how Madara's PS will be look like after he become JJ
Madara had Hashirama's power .... so Madara logically should be able to summon Shinsusenju
And no matter how you explained those questions ..... it will just be as a theory
To sum it up ..... we don't know the full power of 3 eye JJ Madara .