Bachelors thesis supervisor headed for emeritus; professorship won't be restaffed First off, I'd like to acknowledge that I am not sure whether this post fits here, as most discussions on here revolve around higher levels of academic life. Let me know/remove this post if it does not belong.
I am in my final year of studying computer science in Germany. I also study some maths on the side, and intend to complete my maths degree after obtaining my bachelors in CS.
I have found a broad field I'd like to write my thesis on (programming language theory in general or type theory in particular). There currently is 1 professor at our institute who has been doing research on type theory in a programming languages context for a long time, but they are headed for emeritus, which I've learned from talking to current and former students of theirs.
When I asked them about a thesis, their response was rather brief, and could be summed up as

If you can see yourself doing this more or less on your own, it would be possible. I'd recommend a review-style thesis, you don't need to come up with new results. Please look for articles yourself, I am currently ill.

While I know their health situation is none of my concern, I am wondering what would happen if they passed away while I'm working on the thesis (I suspect they might be chronically ill, for reasons I will not go into). Also, I don't know whether I want to put the burden of having to supervise me on them when they're headed for emeritus and possibly not feeling well overall anyways.
This situation I deem is much more common on higher levels of education, such as grad school, so I wanted to ask whether anyone here has had any experiences in similar situations.
I know their professorship won't be restaffed, so there won't be a new professor of programming language theory/type theory following their footsteps. This makes me somewhat sad, since that field interests me the most. There is also the option of external advisory (e.g. professor at a different university), but that doesn't seem practical, as I would need to find a professor (not just any faculty but a full professor) at my institute for assessment of the thesis (which there won't be any of once the current professor officially retires), and this would put a lot of extra work on every involved party (external professor, local professor, examination office, me); on top of that it's probably rather unlikely a professor from another university would supervise me, as I have gathered from other posts on this SE instance, and as I of course don't have any special research experience in the field to offer to them.
Also, I would like to ask whether you have a method of figuring out what to do. I know the basic questions to ask myself are

do I see myself coming up with a thesis topic and finding relevant literature on my own?
would I be fine with writing a thesis in a field I am less interested in but would have safe supervision?
should I even care this much, given it is just a bachelors thesis?

I should probably mention they have 1 PhD student who seems to be in the process of finishing up their thesis, but they don't seem to be willing to supervise students right now, at least that is the impression I got from a past correspondence.
Thank you.
You already gave a good summary with the three questions at the very end.
If you are very interested in the topic, already know a lot about it and can work on your own without much help, then go for it.
If I were you, I would sit down and try to figure out a topic for your thesis. If you have the impression that you have a reasonable idea then ask the professor if this is ok for him. If not, I would think about going somewhere else where you get more supervision.