I have to disagree with with your interpretation that Mr. Bennet isn't concerned about his family's future.

Firstly, there's absolutely nothing he can do about it. No matter what he does, how much he saves or how he acts, the property will be lost upon his death. The entailment is settled.

I believe this is why he allowed Mr Collins a visit. By making amends with him, Mr. Bennet can hope Mr. Collins will allow the family to stay on once he should pass. I even think, if Mr. Collins had shown interest in any one of the younger girls, namely Mary, he may have favored, and even encouraged, their marriage. There's nothing that says Mr. Collins *will* evict Mrs. Bennet and the girls. He could very well allow them to rent the property.

I also think the lack of visible concern of the situation would be very typical of gentlemen at the time. To appear unaffected while being quite the opposite isn't an uncommon occurrence. Worrying is weakness. We know he regrets the way he's done things, not saving for the future in hopes of having a son.