Watson and Usman to open.
"Hussey plays right to Morgan, and Morgan drops easy chance!- Hussey scores 150"
Collingwood lost his form with the bat, no doubt. Even if Morgan scores a 50, Collingwood still adds way more value to the team. As you mentioned experience, great fielder, and not to mention he is not too bad with the ball either. And what makes you think Morgan will show up with the bat? There is a better chance of Collingwood finding his touch than Morgan scoring a 100 in a Ashes Test match. I'd give one more chance to Colly. Then again, I don't know much about the English team.
And I don't blame Collingwood for getting out like that on the last ball of the day. That was all on Pretty boy.