Well, I'm not going to hold my breath on the future of the Durango as Chrysler seems undecided on it and it appears as it might be a sister SUV to the Grand Cherokee (it may not be designed to pull the weight that you are looking for). It can be more cost effective anyhow to keep a vehicle and keep transmissions in them.
As for your father's decisions, I'm going to give you a tip. My father growing up didn't make a lot of sense at times in many of his decisions (especially with vehicles), but ultimately after getting out into the real world I learned that despite the fact that we didn't always agree (me being right of course on the cars disagreements
) and I didn't care for his temper, my father is better than average because he's there for me when I needed help and would do anything to ensure my success and sadly not everyone can say that. I guess my point is father's many times don't make sense, but ultimately they have good reasons for their decisions.