If Denethor hadn't committed suicide

[Rumil]

Nice thread, Just a quick point to throw into the mix,

Gandalf plainly foresaw what Denethor's fate 'should have been' had he not committed suicide-

Whereas your part is to go out to the battle of your City, where maybe death awaits you. This you know in your heart.

I think though that this makes too 'neat' a coincidence, two old leaders; Theoden and Denethor, both depressed by works of the enemy, both healed by Gandalf, both die heroically at the Pelennor.