Basic intuition should tell us that the universe is expanding exponentially. The universe has to expand like that, otherwise it would not exist. I really don't think it has a choice. If the acceleration were slowing, it would mean the universe is reaching a certain "point." And any point is arbitrary making existence "unsupportable." Arbitrary cannot exist on its own.
Even expanding at a specific rate is arbitrary. It has to be an accelerating and un-pinable rate. Anything that could define the universe as arbitrary would cause it to cease existing.
*Asymptotically speaking, a case could be made for a point but... this is beyond my pay grade.