The bible identifies the Christ as a False Prophet

[John V]

Hold on cowboy, Christ says "28 “Assuredly, I say to you, there are some standing here who shall not taste death till they see the Son of Man coming in His kingdom.”

So the burden of proof on you to establish that Christ's Kingdom did not come as described before all of those men died.

An IMO simpler explanation is to consider "see." He didn't need to include that. He could have said "there are some standing here who shall not taste death till the Son of Man comes in His kingdom.” The literal reading of the passage was fulfilled in what John saw and recorded in Revelation. Some people consider it fulfilled in the transfiguration, which immediately follows the above verse.