Probably many Logseq/Obsidian/Roam/Dynalist/Workflowy users would buy the lifetime subscription if they could migrate to Siyuan (it has many advantages over each of them).

A simple plugin that converts [[My doc title]] to a ref link to the corresponding doc (if the doc exists) would probably be enough, in addition to the existing markdown import feature.

Converting links to blocks would be even better (in Logseq, blocks have their hash id directly in the markdown file if internal links point to them. This could be used to do the same conversion for blocks as described above for pages).

I also have to say that just a simple plugin that converts [[My doc title]] to a ref link to the corresponding doc if the doc exists would be enough for me. I am willing to give up the links to blocks if it is too difficult to implement (although Logseq blocks that are linked to have a hash id directly in the markdown file which can be used to do the same conversion for blocks probably as easily).

I would really like to migrate from Logseq to Siyuan but I have thousands of interlinked pages in Logseq and giving up the links would make my notes much less usable. Recreating them by hands is not feasible.

A migration script would certainly increase Siyuan's user base a lot. There have been some frustration in the community around Logseq numerous bugs and some (like myself) are losing patience. Siyuan seems a perfect replacement for Logseq with many added features and improvements such as better search, better app layout flexibility, better sync, etc.

Given that Roam, Obsidian and similar software are based (or exportable to) markdown, my guess is it wouldn't be very difficult to adapt a Logseq migration script to these.

Could that be put in the roadmap?