To be fair the CPTPP already had Japan in it. This just means that instead of a 5% chance of China making it in, it's closer to a 0% chance now. Free trade agreements with members of the US alliance system are basically impossible now which necessitates a faster shift to the developing world.
Much has been said about Chinese de-dollarization but it isn't happening. They've just shifted their portfolio out of US treasuries to US Agencies and other debt instruments. Which implies some level of resistance from within the policymaking circles at the PBOC to serious de-coupling with the dollar system. It is concerning to say the least.
China will join CPTPP. The others inside the CPTPP do not really have a choice.
Some members of CPTPP do not want China to be a member. Other members do.
China will just sign the same agreement with the other members.
Then flood the CPTPP market with goods targeting those who did not let China join.
One way or other, China will assert itself in it own neighbourhood, and especially towards those shits.