Could alien civilizations be too far away to ever contact?

Yes. Alien civilizations could be too far away for meaningful contact, and for some of them that may be effectively permanent under known physics.

Two main limits matter:

1. The speed of light sets a hard limit on how fast information can travel. Even within the Milky Way, a two-way conversation across thousands of light-years would take thousands of years per exchange.

2. The universe is expanding, and that expansion is accelerating. Because of that, some very distant civilizations may be beyond our cosmic horizon, meaning signals sent today would never reach them, and signals from them might never reach us.

So while we can’t say every alien civilization is unreachable, it is very plausible that many would be so far away that contact is impossible in practice, and some may be unreachable in principle with current physics. Over extremely long timescales, expansion also means more and more galaxies outside our local neighborhood will become unreachable.

Caveat: this assumes our current understanding of physics is correct, especially that faster-than-light communication is impossible. If future physics allowed new mechanisms like usable wormholes, the conclusion could change.