Mk 9:1 a failed prediction?

I notice a recent post of James Crossley (Dating the Synoptic Gospels) in which he suggests dates for the canonical gospels. He has a book arguing for a extremely early date for Mk (late 30s) "largely based on issues of law observance." In his recent post he uses eschatological predictions as a indication of date for the other canonical gospels.

I am not going to enter the debate about dating but will only comment here on the relevance of Mk 9:1 as a failed predication:

And he was saying to them, "Amen I tell you that there are some standing here who will not taste death until they see the empire of God having come with power."

In his post James Crossley uses eschatological predictions as a chronological indicator and so Mk 9:1 is treated as a predication of an imminent kingdom:

There are predictions of an imminent kingdom within the lifetime of some of Jesus’ audience (Mark 9:1) and a prediction that the second coming of Jesus will occur within a generation (Mark 13:30).

It is usually assumed that Mk 9:1 presents a failed predication but this is to misunderstand its context in Mk 9:1 in which Jesus has just tried to challenge the disciples' understanding of what God's empire or "kingdom" (basileia) was about (Mk 8:32-33) and Jesus is pictured as challenging the notion of what is true power: followers of Jesus will save their lives by having them destroyed; the Human One will be ashamed of those who are ashamed of Jesus' non-violent kingdom-mission; to attempt to save oneself from physical death is in some sense seen as anti-kingdom and anti-true-power (8:38). In this context we should be willing to take the following mention of "power" (dunamis) in Mk 9:1 in a redefined way.

If we see that the notion of "power" in Mk is not to be equated with natural conceptions of power, then we might take the predication as having come true for all those who did see Jesus' power of resurrection at work. Would not seeing the increased number of believers (who believed in the resurrection and power of Jesus) be seeing the kingdom come with power? Arguably the whole of Mk is to challenge and redefine notions of power so I don't see why we should take 9:1 as a failed predication.