But if Edward had married someone other than Wallis, he might have had children.
Yes he might have done. Although he preferred older women who mothered him so this was less likely. But he could have picked, oh lets say, a 19 year old virgin to give him a couple of sons, and carried on with his mistresses anyway. However he didn't seem too worried about doing that because Bertie had two DDs whom his father George V doted on, the oldest of which would clearly make a good Queen. It wasn't as if he had no heir, he had an heir - his niece (assuming his brother wouldn't live much longer than himself, of course in fact he dies before him).
For centuries Kings have done all sorts of unscrupulous things to ensure that their own personal line continues at all costs - wars, having wives beheaded, killing brothers etc etc. Edward VIII just wanted to be happy with the woman he loved, he didn't want to deceive any poor young wife.
I am not defending him, I think he clearly was weak and a bit thick. However there is a hypocrisy in one minute "the Queen has given up her whole life for this role of unrelenting duty" and "Edward VIII lumbered her with all this" and then the next "Edward gave up the throne so he must have loved Wallis so much" plus the centuries of bloodshed as people tried to get their hands on said throne.
Of course Camilla is divorced and they have been very quiet about what will happen when Charles is King, and fudged the issue by not letting her be the Princess of Wales. But the truth is that she will be Queen - the wife of the King is the Queen and that's that. Times have changed and thank goodness they have.
Margaret chose her position in the succession and the money and the status and the glamour (oh sorry I meant her "duty") over Group Captain Townsend so that says a lot about how much she loved him.