Ok, YAY. I get to try to guess at things.
Baseline before I get started.
First off, I allow for there to be an original 'ourMab' that isn't Murphy first off. I heavily rely on iterations and recursions in allowing for time loops that are identical but then have a slight error that propagate from there. So an insertion of Murphy would be a 'error' though the loop would still be quite similar. Perhaps, we wouldn't know in all loops that Mab=Murphy, maybe we do run across a loop where it's the orginal or and error of an error. So, It's left to some extent as an open question. Thought I do believe we will learn some Mab's real name.
How does Murphy go over a thousand years into the past?
This is hard as it has many possibilities.
1) Time Travel sponsored by Archangel, Mother level entity, Mab level entity, Lady level entity, Wizard (w/Harry?)
2) Time Travel near Demonreach, it most likely has eddies near it that go both forward and backward in time as a result of its creation in 5 times all at once.
3) Murphy say at a Family Reunion that gets transported into the distant past (think Milwaukee disappearing in 1994)
4) Murphy tags along with Sue in TT event.
How does she find herself in a situation where she has enough Fae connection to assume a Queen Mantle?
1) We don't know if she does/doesn't have fae roots. Molly was several generations distant and needed 'rehab' to make her into vessel.
2) She has been at Arctis Tor, been in NN, fought several Fae, killed them, killed Winter Lady, trains with Einherjar whose Lord has a Mask of a Fae King (Kringle), knows that Immortals can be killed on Halloween, knows that Molly was shaped into a vessel for Lady...
How does she skip over being Lady or does she?
1) Theory allows Murphy to become Mab in future without TT (Molly would have to give up mantle or ascend to Mother)
2) Mab=Murphy requires Murphy to TT into past remaining childless as she does so and take out a Winter Lady, or be near one when one dies.
3) She would need to be a better vessel than other potential candidates nearby in the case the Winter Lady 1000++ years ago died.
4) It would need to be during a conjunction or circumstance similar to Halloween, etc.
5) She would need to acquire Lea as her handmaiden
Does this tie into the twitter comment about him writing "Murphy's funeral?"
My guess, Harry and Murphy talk about marriage, therefore "Murphy's funeral" is talked about.
Or, there is WOJ that Harry's relationship don't work out that well, and Jim's answer was like, Yeah, so there will be a reason why Harry/Murphy won't work out, yet.
My favorite would be for her to get picked up by say Mother Winter and thrown into the past. Or, some Fae set out to avenge a perceived insult to Mab for Murphy capturing Harry's heart. And then she gets secretly carried away to appear later down the line. ETC.
I just don't know if it's too soon for Murphy to be out of the picture.
See this post, It has similar thoughts:
http://www.paranetonline.com/index.php/topic,50304.msg2292401.html#msg2292401Excerpt:So, Murphy would be Winter Lady, for how long I don't know (WOJ our Mab as a Winter Lady chose Lea to be her handmaiden). Her appearance would have to already begun to shift. And, then some sudden set of events that aligned with the last time things got awful in the wizarding world, it ended with at least both Mab and Titania dying, who else we don't know, which allowed our Mab, our Titania to assume the mantle of Queen roughly around the time of the Battle of Hastings. Around that time, Mab and Titania stop speaking. Give us 1000+ years and I don't think we can assume we would be able to identify that Murphy that had been Mab for 1000+ years is our Murphy. They'd look totally different. So, that is one thing my theory counts on, a mask for Queen Mab that camouflages her identity, which will stun us when it is revealed.