Since Dark Energy is a fictitious force, any assumption with regard to it is perfectly valid.
You can consider that it will decide to accelerate or stop the Universe altogether.
Dark Energy is a fitting parameter in a non-Fundamental theory. This is what you do when you have the faintest idea on what is happening.
If is shown in the expression for the Hubble parameter (not a constant any more)
It corresponds to the where DE is Dark Energy.
So, no matter what you decide that Dark Energy will do, you will always be at the same level of knowledge as the smarterest scientist.
On the other hand, if you decide to look into a Fundamental Theory that has a solution to your conundrums, you ca look into the Hypergeometrical Universe Theory (HU).
This theory has been systematically censored by the community. I say community because as you know:
This theory predicts all the type 1a Supernovae distances (from their redshifts z) as:
Those distances are predicted by a HU d(z) function (a.k.a. Cosmological Ruler):
Which is parameterless, that is, HU predicts Cosmological Observations without a single parameter. No parameters means no Fictitious Forces (e.g. Dark Energy), or immaterial matter (Dark Matter).
Whatever you say about Dark Matter and Dark Energy is likely to be as plausible as anything coming out of the mouth of the smarterest scientist you can find… It is just nonsense.