Will politicians continue using Twitter et al after this? Seems a bit risky to reach out to their followers using a third-party. Why don’t they have their own website?
Those official communications–anything "from the office of"– should be released through official US Government channels.
Regardless, unless you're planning on inciting a raid on the capitol, you probably won't be banned as a politician. Twitter literally bent over backwards to still allow Trump to use Twitter even though he consistently broke the platform's rules.
I don’t see a reason why most mainstream politicians need to distance them self from this platform in light of this. I’m sure most main stream politicians do not associate them self with the type of rhetoric that got Trump kicked form the platform, and are fine with continuing to use it.