I don't know when it will be included as part of the subscription in Claude Code, but at least it's a paid add-on in the MAX plan now. That's a decent alternative for situations where the extra space is valuable, especially without having to setup/maintain API billing separately.

Based on their API pricing a 1M context plan should be 2x the price roughly.

My bets are its more the increased hardware demand that they don't want to deal with currently.