There was a debate in the comments to those posts as to whether the expanding diagonal triangle is a recognized form to end a move, and a few days ago Kenny came back with an update himself supporting the expanding ED. He shows this chart, which is from Prechter's Elliott Wave Principle (10th Ed., 2005), p 39. It shows an expanding ED ending a pattern, and (note to Vipul) shows the swings of the expanding ED largers than the prior wave 4 of higher degree.
Kenny's discussion of this topic is well worth the time. He also points to a resource that I had mentioned in my longer treatment, A Slight Excursion into Ending Diagonals and Other Terminal Patterns that should be studied as well.
A footnote on terminology: what Prechter calls an ending diagonal, Neely calls a Terminal Triangle. As is his wont, Neely adds more restrictive rules onto his Terminals. He doesn't label an expanding ending diagonal as an expanding terminal triangle, but he has a form called wave-5 extended which fits. It would give a target of Sp1275 by June. Neely also allows for an expanding triangle to end a complex correction, a form which may fit the Kenny pattern and would support an end last week.
Orthodox wave theory teaches that triangles are almost always penultimate waves, typically in waves 4 and B, so it may surprise to hear of triangles ending complex corrections, but the concept is also there in Prechter's EWP. He also thought complex corrections would be sideways, whereas this Hope Rally is elongated upwards, yet he has been counting it as a complex correction with multiple X waves, not an impulse. Orthodox theory also says that ending diagonals are rare, but Kenny and others have seen an increasing prevalence of ending diagonals/terminals lately. Orthodox theory also expects expanding triangles in fourth waves, but Neely says he never sees them; instead some other wave pattern is happening, likely a terminal fifth wave which looks like a triangle. All of these points suggest an update of wave theory is overdue.