Potential is identity viewed from epistemological perspective, a mind with memory and imagination. All that exists are particulars, doing particular definite things in accordance with their identities. It takes imagination or memory to divert the mind's attention away from what the object of the mind's attention is doing right this moment.
'Potential energy' is a concept taught in elementary physics classes. Pendulum motion is described using the principle of conservation of energy such that the sum of the pendulums kinetic energy of motion and its potential energy of position must remain constant (neglecting friction for the moment). Here the so-called potential energy is real and actual because the pendulum is a real and actual existent with a real and actual position within a gravity field at every instant. One can avoid the potential confusion of thinking of potentials as real because it appears in an equation describing the pendulum's motion by using the term 'energy of position' instead.
This kind of statement "a sea battle either will happen tomorrow or not happen tomorrow" is formally true because the alternatives are mutually exclusive and jointly exhaustive, but it does not constitute knowledge and cannot be categorized as a fact because it does not predicate anything. (It predicates two perfect contradictories which cancel to net zero predication.) The grammar of the statement is correct, the logic of the posited alternatives is flawless, yet it remains entirely an exercise in method. It is an unfalsifiable statement of the kind Popper scorned. The statement employs the useful and valid concept of "tomorrow", but that does not transform the referent of "tomorrow" from an epistemological construct (a 'concept of method' in Objectivist jargon) into an existential fact.
Tree rings exist in the present as an effect with a cause in the past. The cause existed, then the effect existed. The present existence of the effect does not require the present existence of the cause.
Going back to your argument:
No beginning and no end can still be literally true if a finite Universe had some kind of strange asymptotic boundary conditions governing time. For example, space and time are related such that a very high mass density implies a very high space time curvature such that time slows to a crawl relative to a lesser curvature. The Big Bang would have played out very slowly, and extrapolating backward in time beyond the Big Bang requires crossing an inflection point where time would not pass at all. A remote future in which all matter had entered black holes and then been re-radiated as Hawking radiation until all the black holes were gone would be a perfectly static universe in which time had no meaning.