You mean An Adventure in Space and Time. :P I had to check my copy of the DVD to make sure I had the right title. I keep wanting to call it "An Adventure in Time and Space" for whatever reason, and I can never which of those two is correct. Anyway, yes, it makes sense in hindsight -- but since that special came out in 2013, it doesn't exactly come across like they were hinting at any plans to bring back the First Doctor in the actual show. It's just... not something I expected to happen when the special came out, and so, not something that I was really waiting to see in the future. XD
And yeah, I saw all the references to Susan and I hoped that was going somewhere. But I assumed what they were planning on doing was having the Doctor finally go back to 22nd century earth and visit her again.
You know, like he promised he would, way back when.
With the speech where he promised he would come back being one of the most iconic moments from Classic Who, and probably the most iconic moment from Hartnell's era specifically.
...Which was even referenced in An Adventure in Space and Time, several times. With one of those times featuring the original clip from the actual episode featuring the real William Hartnell, as opposed to David Bradley.
And yet, about a dozen lives later, he still hasn't ever gone back for her.
...Aaaaand then I almost forgot about all the Susan references entirely when the end of the season drew near with them still not having done anything about that.
Also!! If One and Twelve are both the first incarnation of their respective regeneration cycles, and they were both killed by Mondasian Cybermen... I wonder if we can expect that pattern to continue... maybe Thirteen will be executed by the Time Lords, and Fourteen will be killed by radioactive spiders. I suppose we'll have to wait and see...