In all honesty, post-Schmidt the Ireland job shouldn't actually be that sought after. Don't get me wrong, they are a cut above everyone else bar NZ as a team at the moment, but that's exactly why it's somewhat of a poisoned chalice - good luck Faz Snr.
Sexton, O'Mahoney, O'Brien, Healy, Best, Toner, Kearney, Earls and Murray are all in or close to their 30s. I'd be surprised if many were around for the 2023 world cup. There are plenty of good young players coming through, but starting from a world ranking of 2 and being comfortably the best Ireland team this century, means that there is not much higher to reach and a potentially very long way to fall.
On the flip side, all of England's key players are 27 or younger. This means that a coach taking over post 2019 would have the best players hitting their prime come the next world cup. England also have had, by far, the most successful U20 team over the past 6 years. That means there should be no shortage of talent coming through.
Other things to consider from a coaching perspective, beyond expectations/starting point and player pool are; the relationship between the top flight leagues and the union (Celts and SH win here), money (France and England), media scrutiny (Celts, Aus, Italy seem kinder/more supportive or less interested) and of course potential for success. With all of those in mind I would rank the desirability of coaching jobs for top tier nations (based on Rugby Champ + 6 Nations participants) in rugby as follows:
1. New Zealand (potentially only 1st for a NZ native)
2. England
3. France
4. Wales
5. Ireland
6. Italy
7. Australia
8. South Africa
9. Scotland
10. Argentina
Thoughts?