I have struggled with the thoughts of wanting to move on to 4D, but I realized lessons will come wherever I am, appropriate to my needs and to judge the lessons in this life, in this density as somehow less than what would come in 4D really doesn't make much sense.
Ultimately, it comes down to whether you are acting with growing awareness or reacting with ignorance. You will be where you need to be appropriate to your level. This is the universe, in all its divine wisdom, unfolding as it should. The most we can do is focus on growth and service, let go and let the DCM take care of the rest.
To worry about being left behind, to want to be in another density, to fear being blasted back into the primordial soup are all an incorrect use of energy and a form of lacking in faith in the DCM, OSIT, not that my mind doesn't occasionally go there as well.
There's sometimes a subtle difference between advancing oneself because it is the right use of energy versus advancing oneself in the hopes of avoiding certain aspects of a density shift.
We are tempted to assign value in terms of "graduating" or "failing" when, in reality, we need to be precisely where we are at any given moment, not because we want to or because we subjectively perceive it to be right, but because we fit.
I find this thought particularly difficult to communicate, so I hope I have expressed it well enough.