written out who? Howard? For what? At that point it didn’t matter since it was the first sequel and RDJ was the star.
As for Sif, the actress couldn’t do it because it conflicted with her schedule. She was doing another project. This is why Marvel started signing actors to contracts that locked them in for multiple shows in addition to other clauses. Renner actually got tired of it. Oscar Isaac wasn’t going to do Moon Knight if he had to sign on for multiple projects.
And for the record, Portman left the MCU and they wrote her out. They didn’t try to replace her.
Yeah blah blah blah .. reeasons reasons reasons .. .but they did it did the switches didn't they. Sif vanished for almost 10 years worth of movies and people reason it away.
Stark as well for example. They keep flip-flopping between the two actors. Two actors mind you who look
nothing like each other. One with a fat round head. The other with a thin head.
Additionally about Thanos (for example) he looks nothing alike in IW/Endgame compared to his early apperances. The character look and movements totally different.
We even had two actors play the same "person" (somehow) with no in world explanation given whatsoever .. Pietro aka Wanda's "brother".
etc
That is not being "consistent" in my book.
Even when importing actors from the other worlds people have to invent reasons for a different look. Foxx for example but we reason that away.
People are able to reason away all of that and more away somehow .... As you will now no doubt continue to do ... but BP .. "nah never dat" !