Hi there,
Unfortunately we haven’t been made aware of a timeline for this just yet. The Google team may have more insights on this and asking the same query at the Analytics Help Center may yield more insights. You can also find a related GitHub issue on the AMP frameworks GitHub repository.
In the meantime you can use a Universal type property alongside a GA4 property for your non AMP URLs, while only using a Universal type property for your AMP URLs. You can use Site Kit plugin and paired AMP (via the AMP plugins reader or transitional mode) in order to ensure you’re tracking both versions of your site. Once the Google Analytics team have full AMP support then this will be implemented within Site Kit for AMP URLs also.