I see big problems here like inheritance tax.
Now, thinking very simply, even completely without tricks—that is, without looking at "how can the property be transferred particularly cheaply"—if only the gift/inheritance tax would apply, that would already be significantly less. If I calculate roughly right now (200k property value minus 20k allowance times tax rate—I believe 20% for this degree of relationship and the amount of the gift), that would be about 36k? Then the question is whether the dilapidated house might reduce the value and whether parts of the property are garden land or similar and, for example, an expert might come to a lower market value. But IF you could really imagine the property for yourselves (which tended rather towards no), that might be within an affordable range for you even if it wasn’t the 200k. Although perhaps one problem is that the uncle wouldn’t get anything at all. It’s definitely important that the uncle doesn’t risk impoverishment (that can cause problems with gifts). Otherwise, maybe long-term he himself might not find it so appealing either—you might know better how he is personality-wise. There are definitely people who, after decades, still reproach you with things like "without me, you wouldn’t even have the house!" or something similar—that’s something I personally wouldn’t want to deal with. But that very much depends on the individual. Of course, there are also mixed options, but I just wanted to start from the simplest... Otherwise, if nothing is arranged and he dies, then yes, inheritance tax will be due. He also seems to have other assets (at least his own house), so presumably a considerable amount would come together and an optimization would probably be worthwhile. But on the other hand, that is offset by the inherited assets. It naturally feels frustrating if money just disappears into (what feels like) "nothing" (i.e., goes to the state), but on the other hand, there is still the option to sell parts (or even all) of the properties to cover that. So I understand that it feels super frustrating when, for example, out of 1 million (his property + additional land + possibly other assets), the tax authorities take 300k or so, and at least part of that could have been avoided. But then there is still the option at that time to sell parts to cover that. And I think if currently no one wants to deal with "inheritance optimization," then you can’t force them to do so. You can only point out how unfortunate that would be, but in the end, it’s your uncle’s decision what he does with his assets during his lifetime. Fundamentally, it may be somewhat complicated to organize all that in the event of inheritance, but presumably, you’ll still be pretty well off in the end. Of course, if, for example, it is very important to the uncle or the rest of the family that the house and property remain in family ownership even after death and that might not be realistic without prior arrangements OR they would be very annoyed by the taxes incurred themselves (you also mentioned your parents and grandparents, who are ahead of you in the line of succession depending on how life plays out)—then that would be the starting point for conversations and advice. Maybe it could be something like, "I don’t want to deal with it, but if you take care of it, I’ll listen/maybe join in," and it could be an option that you get advice yourself first and then, when you have rough proposals, involve your family more to concretize that. But if they completely shut down, then you really can’t do much in that direction. (No idea if it might make sense for you to have a rough plan of what to do in the event of inheritance so you’re not overwhelmed if the time comes—but that then has less to do with optimizing inheritance tax.)