Don't be silly. Of course we do. We know the universe is expanding. If the universe was infinite, then it would necessarily by definition be eternal. The 2nd Law states that the entropy of closed system will always increase over time. Entropy is the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system. This does not prove chaos or randomness in the way many imply. It only conveys a loss of thermal energy for conversion into mechanical work. Loss of thermal energy for conversion into mechanical work does not mean the matter within the closed system cannot be orderly. What it really means is that there is a cost for every exchange between matter and energy. Furthermore, the 2nd Law of Thermodynamics proves that the universe had a beginning because if the universe were eternal (i.e. expanding and infinite) there would be no usable energy left within the closed system.You don't know if the universe is finite or not.I'm not an astrophysicist, but odds are they know more about this than you or me.It's is currently impossible to predict the future, let alone the very distant future. Maybe the universe starts to slow down in 100 billion years?
OTOH, math is math and physics is physics. Newton's laws of motion apply. Mass doesn't suddenly slow down and reverse direction without a reason. The science, as the links noted, indicates matter is accelerating as the Universe expands. Why is unknown, but there is no reason to think it would suddenly stop and reverse direction.