"Always" changing is a paraphrase of "continually" changing, which is a "more precise" formulation. "continually" does not have the connotation of "allness" for all time; it has a connotation more of an on-going process. One way of characterizing the difference is that "always" takes a "global" perspective while "continually" takes a "local" perspective. But "global" perspectives are "inductive generalizations" from a remembered sequence of local perspectives. We experience "local" perspective directly and immediately, but we can only construct a "global" perspective by abstracting from our memories of prior local perspectives. Milton has proposed using the term "intra-personal" "time-binding" to cover the ability to remember the past and form new abstract generalizations from it. I just call it our ability to remember and to abstract from memories, because I would reserve the term 'time-binding' for the transmission of information from one person to another - usually involving a recorded medium.

Another less precise formulation often used, "constantly changing", is an oxymoron in that it appears to be "self-contradictory".

The very nature of "change" is implicitly problematic because it implies that there is something that existed before the change that continues to exist after the change, while at the same time there is also both something that existed before the change that no longer exists after the change and something that did not exist before the change that exists after the change. Does this wording make your head spin? You're in good company, because the discussion goes back more than 25 centuries. Read De Generatione et Coruptione and, if you dare, read a translation of the source reference.

While "motion" side-steps the question of change, that does not deal with the problem of "always", an "allness" statement. Your choice of "ongoing", it seem to me corresponds to my word "continually". The "process principle" goes back to Heraclitus and the theory of flux (http://www.xenodochy.org/gs/heraxeno.html). Science seems to have corroborated this perspective over the millennia. Korzybski adopted it.

We model physics in term of mass (M), length (X), and time (T). We model motion (V) as the rate of change of length with respect to time (V=X/T).

Could we model physics in terms of mass, motion and time, making length the derived or abstracted quantity (X=VT)?
Could we model physics in terms of mass, motion and length, making time the derived or abstracted quantity (T=X/V)?

By using simple algebra, it looks possible, but when calculus is invoked, V=dx/dt (currently), so we would have X=[integral]Vdt or X=[integral]Tdx in the former case and T=dx/dv in the later case.

We can easily conceptualize time, space, and mass, in terms of our direct perceptions, as dimensions, but we don't currently have a direct or learned perceptual way to conceptualize velocity as a dimension, and that is what would be required. Plus all the laws of physics would have to be rewritten. Does anyone remember the complicated way the motion of the planets was described when the earth was taken as the center of the universe - with cycles and epicycles? How simple things became when the sun was made the center - with the planets traveling in circular (elliptical) orbits. Viewing physics using a model that takes velocity as a primary dimension would correspond, in complexity, to the model of planetary motion using cycles and epicycles.

The standard model of physics conceptualizes the universe primarily as a four-dimensional space-time continuum with mass as a varying local property. We could call it a five-dimensional space-time-mass continuum. Motion, or Heraclitus's flux, is only characterized it terms of how the three dimensional coordinates of space change as we change or move along the time dimension. If we "step outside of time" (conceptually) we view the prior and subsequent space coordinates correlated with the prior and subsequent time coordinates, where "prior" means numerically less than. "Motion" is only meaningful in terms of altering the time coordinate. The general semantics notion of flux or "continual change" can only be meaningful from within the time dimension as we advance. It is not meaningful in the atemporal four(five)-dimensional space-time(-mass) perspective. I present a nice metaphor for here.

All this raises a question. Is the general semantics notion that "things are continually changing" scientifically current?

So, we've taken the original question, Does the statement "In the universe, things are always changing" contradict general semantics principles? and apparently abstracted to a level that questions whether the general semantics perspective on change is itself a restricted and less general view. Does it appear that the general semantics view is limited to traveling in time? That it does not encompass the greater, atemporal, perspective, from which traveling in time is just a limited and restricted view (in mathematical terms a projection onto a subspace)?

IF "two things" are "identical" (in all respects), then there aren't two things, but only one thing talked about twice.

Since we have not experienced the entire universe, from beginning to end, then we do not know that "things are always changing". We only "theorize" it. It is a "judgement", an inference, a projection, an abstraction. It is also a "self-sealing" doctrine, because we have no way to disprove the claim. I consider it simply a way of viewing the universe from the perspective of "traveling in time" that is hypothesized based on our current, very abstract, scientific model of the universe. Remember "always" changing is an "allness" claim, and general semantics says we should not do that - at least the general semantics that I am acquainted with.