“I doubt it. Ireland, UK, Bulgaria, Croatia, Cyprus and Romania are not party to the Schengen Agreement”
Three of those nations are island nations (if you accept Ireland as an island, with its only land border being another non-Schengen nation). The situation for island nations is, thankfully, not quite so critical as for those with land borders with other Schengen nations.
Four of the six (all bar the UK and Ireland) – along with all new members - are legally bound to join the scheme and will do so in the not too distant.
“The current immigrant/refugee problem is very serious but it will settle down and be resolved.”
Not even the most liberal of observers expects that, Eddie. Most people believe that, so long as Europe allows boats to land then people will come (and even if they don't , people will still come).
“The UK being in or out of the EU will have an effect for centuries ahead, long after the present problems are forgotten,…”
The EU (with or without the UK) will not last for centuries, Eddie. It is doubtful if it will survive the first half of this one. It is an outdated relic of the past which should, and will, be consigned to the dustbin. The only question is how much more damage it will inflict on its hapless members before that happens. Whether the UK wants to be part of it when it is eventually binned is the question people should ask themselves. You are quite right; there’s far more to the question than the Syrian crisis (upon which a “Brexit” will have little influence).