However, whether or not the Diamond would be able to withstand over 30 years of flying school use, is another matter
The way things are going with engine replacements they probably will still be around in 30 years time - still waiting for the original engine to be replaced.
How can you tell I'm not impressed with Diamond / Thielert? The DA40TDi is probably going to be grounded for several months as apparently there isn't a single replacement engine to be had anywhere in Europe.