nprofile1qy2hwumn8ghj7un9d3shjtnddaehgu3wwp6kyqpqjd874v63430gng67kpw5m597f34dr9vr0yhkp8dkmnma8208raysyd6kk0 (nprofile…6kk0) I guess it depends on what an archival format is for. If the archival format is for making sure that what you publish will be able to be read *in some way* in the future, then HTML makes sense. If the archival format is for making sure that what you publish will be able to be read *in a way adapted to future standards* then I feel like there is an argument for XML, because XSLT allows it to be flexibly processed.
I do actually think that XML output is one of the killer features of forester, because it allows the LaTeX output to be endlessly customized once you understand a bit of XSLT.
Also, you should check out Xee: https://blog.startifact.com/posts/xee/, which is a modern XSLT implementation. If this ends up being what you want to use, I can help to bundle a statically compiled version alongside forester.