It could be said a good set of irons could last you 15 years if you regrip them and look after them regularly
That’s not what the marketing departments say! “The new TaylorMade MX add 20 yards to your shots!” - I should be driving the ball about 500 yards by now!! (lol)
But they won't be out of date! Just because new models come out, that doesn't mean that the old models suddenly stop working. Just buy what you want and keep them for 5 to 10 years if they suit you. There is absolutely no need to change a set of irons more often than 5 years unless you have bought a bad set that don't suit you.
Yes they would do a beginner. They are a good quality set and much better than the cheap ones that throw in every club but won't last. There's no reason why these clubs won't still be fine in 10 years......certainly 5.
I agree with you about 4 irons being hard to hit . 5 irons are easier and I’ve clearly not practiced enough with hybrids as I’m hopeless with them (lol)