Analogies are not perfect. Anyway, “the other shore” would be totally different from this shore, no 5 aggregates, no 6 sense bases. No rebirth, no suffering.
We have to go a bit into philosophy here, but I am not an expert in this, I may mess up some terms.
When you say no another shore, it seems like you only recognise that only something can exist, and nothing cannot exist.
Similar to some ancient greek philosophers who just say vacuum cannot exist, space must be filled with atoms, or something, even between the sun and the earth.
Yet, when atoms comes into the picture, there’s empty space between the atoms, which doesn’t bother people. We cannot say the empty space do not exist. Or else there is no way for the atoms to move.
Anyway, this is also a crude analogy. Just to make the point that nothing existing is not ontologically impossible. I am also just using a crude “nothing” to describe parinibbāna, which is actually beyond concepts, because no mind sense base to think of concepts there.
Functionally, one should just see what’s the function of the other shore, it is to cut off rebirth, and end existence in this near shore. In that way, it can be seen as existing.
Perhaps we can misuse a bit of the analogy above too, on empty space, ignoring general relativity for now. Space without being affected by matter (assume GR is not true) is stable, not disintegrating, constant, yet not matter, not time, not light, etc… Nothing, level 4 nothing from the video below.
But anyway, this No rebirth - what happens next? - #152 by NgXinZhao already gave the sutta’s indication of how nothing can be called happiness.
See this: "Level 9th of Nothing" - Does this sound like Nibbana to you? - #24 by NgXinZhao for a good mapping of the various nothing I have used here. Parinibbāna is the level 9 nothing. A nothing so nothing that to use nothing to describe it is an insult to it. So it’s beyond concept.