What will determine the end of this Holocene era and thus the start of the next era?

Humanity will be the cause of the next era. There are currently just over 7 billion humans contributing to the earth's biosphere. There has never been an animal on the same size scale as humans that numbered anywhere near the 7 billion range. Even the bison of the great plains only numbered in the millions. Once it has been shown that humanity greatly influenced the thaw between ice ages, (ie. seas levels rising faster that at any time in history) all doubt of a new era dawning will be erased.

Sapiencene ?

Sapiocene ?

Humanicene ?

The end of one ERA and begining of the next ERA is usually caused by a bacteria getting into one ERA and causing an ERA ache, which ends with the bacteria being vanquished by either a knight in shining armor or a doctor. This signifies the end of one ERA ache and begining of another. Era are different than Ages or Eons or Periods. Why periods are nothing to speak of, we had seven of them every day when I was in High school. Eons are almost as insignificient, I usually Eon several times before going to bed every night. Ages are not much either I have two children with different ages at the same time.

So the answer is that the ERA ache is the one to watch out for and the change over is usually bacterial.

The next glacial sea level lowstand. This will concide with the termination of the current warm phase of the MIlankovitch Cycle.

it will be the rise of zombies

the next epoch will be called the Zombiecene

The harbinger of the next era will be Jesus as he returns from heaven. All sinful species will be left on Earth while all true believers will be raptured into heaven.

a mass extinction