I personally like this idea. Especially the "get-the-heck-out-of-there before being seen or blown up" bit.
Even though it's been said that the RP's world was a weirder before M's death, this sub-arc gives us a chance to make old Dues Ex Machinas and Ass Pulls less so without changing events outright (semi-retcon?). Plus it allows newer PCs to possibly meet God-level Legendaries that are so hard to fit into current plots.
Notably, this would require players who are still active and were involved in the events help so things don't go too far off course.
to make things simpler though a Sliders approach may work best (Remember that show?); Basically it's, "Group arrives at point A. Group must get to point B in X amount of time or GAME OVER. The time limit is in place to keep the group from getting too involved with past events, but forces them to move along with the past team to get to point B - which would always be near, but not where arc finales took place.
We shall defeat legions of Cipher Peons... by performing an elaborate musical number!