Diesel isn't a requirement for me, but a manual is; a "good" automatic is still an automatic and I won't touch it. A range of legitimate priorities have been expressed in this thread, but my own are that I don't want driving modes, predictive shifting based on learned habits, or anything like that. I just want to row my gears in peace, without computer intervention. This situation is full of unknowns, but the only thing I am absolutely certain of at present is that nothing is going to get me into a car with an automatic transmission of any kind. I'll abandon MPG, cargo capacity, anything before my clutch pedal. That being said...
I forget exactly when, but BMW stopped offering manuals on their wagons a while ago, and the used selection is very slim. They're out there, but you have to want it badly enough to conduct a nationwide search, with all of the expense and logistics that entails. In all likelihood I'd end up in a GTI or Mazda3 (or, less likely, one of the three-box cars I mentioned) before that happened. If I was looking for a buyback replacement and stumbled upon a used 3-series wagon with a manual in the right place and time, though? It could definitely happen, especially if it's an E46, but the odds of ending up in that situation are low.