Potential Distant Future Reversal of Universe's Dark Energy Scalars?

Question

Assuming the most probable universe topology/parameterization -- a infinite flat / open universe following the Lambda-CDM model -- and most possibilities postulated on the long term evolution of such a universe as summarized by Adams and Laughlin's seminal 1997 review, a couple big questions remain. Can anyone provide answers to the following list of questions regarding the postulate late stage fate of the universe and its behavior per our best understanding:

1. Some articles I've read seem to indicate that indeed velocity will approach some maximum limit less than the speed of light, but did not explicitly state that. Will a surviving body of mass m in the late stage universe eventually reach a maximum velocity, and if so what postulates exist for what that velocity will be?
2. Assuming most energy is carried by electromagnetic radiation travelling at the speed of light and that the final velocity of these late stage masses is less than the speed of light, is is reasonable to state that any surviving body of mass will no longer receive energy both due to the combination of the slow emission of energy in the black hole era, the slow speed of mass in the black hole era relative electromagnetic energy emission, and faster than light relative speed between masses in the black hole era?
3. Can it not thus be assumed that if we take this expansionary halo gradient of electromagnetic density and define dark energy as vacuum energy, "i.e. the cost of empty space", that the inward (relative the origin of the Big Bang) "gravitational equivalent"/pressure (i.e. dark energy) exerted on the mass within the expansion sphere would be greater than the outward energy as the dark energy is proportional to the energy density and the inner energy density exceeds the outer (relative the expansion sphere)? (This is in effect the title question -- would the dark energy scalars eventually reverse, exerting inwards pressure / deceleration?)
4. Further if gravity can act an an infinite distance (infinitely beyond the Hubble sphere), won't remaining masses exert some centralized pull towards the point of origin of the Big Bang?
5. If all remaining mass seldom interacts as it slowly decelerates and then reverses direction towards the origin due to the cumulative unbalanced effects, won't this -- assuming sufficient starting mass and hence sufficient relative surviving mass -- create a central singularity of mass whose rate of growth greatly exceeds any escaping Hawking radiation? (Especially since hypothetically any Hawking radiation would for a time be largely absorbed by incoming particles, slowing them but not enough to prevent them from reaching the singularity.)
6. And if all of the above hold basically true, wouldn't that potentially lead to a massive warp in space time effectively folding the once-escaped electromagnetic energy closer to the singularity composed in part of the mass ancestors of its historic source leading to a future big bang? Has anything like this been proposed? Or does some breakdown in the above chain of hypotheses preclude such a distant future timeline?

Answer 1

1. Some articles I've read seem to indicate that indeed velocity will approach some maximum limit[...]

Space expansion is distinct from 'velocity' which is used to describe local motion. Space expansion produces a 'relative velocity' which has no limits. See: Can space expand with unlimited speed?, and How is it possible the universe expanded faster than the speed of light during inflation?

2. [...] is [it] reasonable to state that any surviving body of mass will no longer receive energy [...] in the black hole era?

The universe will asymptotically get colder and colder (both individual objects and the background radiation), and objects will receive less and less radiation. Light always travels at the speed of light relative to an observer.

3. Can it not thus be assumed that if we take this expansionary halo gradient of electromagnetic density and define dark energy as vacuum energy, [...] that the inward (relative the origin of the Big Bang) [...] pressure (i.e. dark energy) exerted on the mass within the expansion sphere would be greater than the outward energy as the dark energy is proportional to the energy density and the inner energy density exceeds the outer (relative the expansion sphere)?

This doesn't make sense to me as a question. But let me address what I can: There is no center of the universe / the big-bang did not happen at a certain location in the universe (see: Did the Big Bang happen at a point?). The only inward "pressure" is from the gravitational force, which already is weaker than dark energy, and will only continue to weaken --- so there is no reason to expect a reversal of expansion.

4. Further if gravity can act an an infinite distance (infinitely beyond the Hubble sphere), won't remaining masses exert some centralized pull towards the point of origin of the Big Bang?

Gravity cannot act at an infinite distance, it's propagation is limited to the speed of light (e.g. How fast does gravity propagate?), and thus it's influence to the cosmological horizon.