He threw one old lady under the bus to speed up the process. He wasn't cheating them. And he felt so bad ruining her social life that heb sabotaged his entire practice to try to rectify it. It was a scumbag move, no doubt, but that was him straddling the line to go after money he had earned without waiting on it.
I don't see how that suggests he'd try to scheme his way on to Chuck's estate if Chuck ain't leave it to him. He knows it ain't his and he's never expressed any desire for it.
You missed or overlooked a few things. 1) Jimmy was a criminal before entering law. 2) Jimmy was and still run scams. 3) Jimmy have forged legal documentation BEFORE to serve a purpose...so how you THINK he couldn't go there again? 4) As evil Chuck is, he spoke the truth about Jimmy which is no matter how much of a "noble" act Jimmy claims to be trying... no matter how so-called "guilty" he may pretend to be, Jimmy doesn't really care unless it is SELF-SERVING. 5) This show is called "Better Call Saul" is it not? So the evolution of Jimmy into Saul Goodman is almost complete. The only thing stepping in his way to verge into full Saul Goodman persona is Kim. Once that relationship is broken, there's nothing morally ethical he would no do and Chuck made it absolutely clear that he NEVER LOVED HIM. Jimmy ALREADY was the reason Chuck's insurance was fuccked over and that was only out of spite! So you assume Jimmy wouldn't even attempt to get his hands on that wealth by any means necessary? How else you would assume Saul got so-called rich in Breaking Bad?