ARM was originally a joint venture of british Acorn Computers, Apple, and VLSI. There will be no ARM without investment from Apple back then. Their history goes all the way back and Apple used their ARM processor in the Newton back in 1997.

It it is still incredibly good deal for ARM to get all the fees for selling instruction sets. Apple still needs to design their processors themselves and pay for manufacturing.

This may change in the future when RISC-V may or may not take over. But it seems ARM will be ok for next 18 years with Apple contract.

PSA: Apple’s new Journal app won’t be available on iPad and Mac at launch

This means Journal will be avialable in soon after.

You may be correct. They will put micro-LED into their flagship MacBooks.
The “SE” MacBook may rely with normal LED they use on older models.

I am sure they have finished design at the studio. But at the end it is up to business team to see if it makes business sense for them. My feeling is that it may be not making much sense at the moment when “cheaper” models are generally older generations of their products.

You can still buy their MacBook Air with M1 from 2020. That is nearly 3 1/2 years old computer. There is no need for them to cheapening the brand at the moment.