Upcoming house purchase: buy with or without leasehold rights?

The leasehold contract expires in 2052

And then? Then you no longer have a house. It does not continue automatically; unless you have agreed with the lessor in time. Usually, the leasehold is then significantly increased.

If you do not agree, the house is no longer your house, and you receive 2/3 of the market value.

On the other hand, I will be paying off the house for the next 13 years and will be debt-free afterwards.... and could then set aside 300€ monthly to save for the purchase of the land [...] But who knows what will be happening in the year 2052....

A matter of attitude.

People who accumulate their capital in long-term investments with high returns (simple buy & hold of stocks, for example) would clearly tend to deal with it only in 2052. If something comes up, you have the money anyway. But if you’re dead by then or Europe has collapsed, it doesn’t matter either...

However, you give up the good feeling of closing the deal early and being prepared for all eventualities.

I would urgently recommend that you choose what feels better for you anfühlt. You want to maximize your quality of life, which cannot reasonably be calculated against money. At any rate, not seriously given the long period until 2052.

2052. Expiration of the leasehold. Unlikely repurchase by NRW: They then have to buy the house from you at 66.66% of the market value valid at that time for everything. More likely: New leasehold. However, it will certainly be higher. Market-based in 2052. Approximately 2-4% of the land value applicable at that time per year. Also quite conceivable: They offer it to you for purchase alternatively in 2052. I would talk to the leasehold grantor....Karsten

2052. Leasehold expiration. Unlikely repurchase by NRW: They then have to buy the house from you at 66.66% of the then applicable market value for everything.
More likely: New leasehold. But that will certainly be higher. Market-based in 2052, of course. Approximately 2-4% of the then valid land value per year.
Also quite conceivable: They offer it to you for purchase alternatively in 2052.
I would talk to the leasehold lessor....Karsten

but then not at the 86k (?) I can't imagine that

Yes, it is probably really an emotional decision. Is there a listing of the trend for standard land values from the past until now? That way, one might be able to look a little into the crystal ball.

If you already start like this, like crystal ball gazing, buying directly is the mentally healthier alternative.