Alternatively, I can think of a solution where it would be possible to optionally indicate the method of swapping by which the given element is to be explicitly replaced. Example:

<a href="/" hx-replace="#content,#sidebar:morphdom,#list:beforeend">

... so #content will be replaced by default swapping method, #sidebar by morphdom extension and #list by beforeend. This nifty functionality would solve many, many useful scenarios.