Ultimately, the answer comes down to fate of the euro. It's the linchpin to everything.
From the point of view of one who has travelled fairly frequently in the Eurozone I can tell you I find the euro very convenient indeed.
In my London merchant banking days, when I used to go on marketing trips around continental Europe, I found that while the excellent European train service was a pleasure to use, the proliferation of local currencies made travelling a pain.
There was nothing more annoying than to be on a long-distance train that had just crossed the border from Belgium to Germany at Aachen, only to discover that I could not enjoy the excellent Deutsche Bundesbahn bockwürst and fine local beer because I had only sterling and Belgian francs in my wallet, but no deutschemarks!
The other problem was that after a long trip I ended up with my wallet stuffed with small amounts of ten different currencies, none of which could be changed back into anything useful because the bank charges ate up their value.
In southern Europe, local exchange controls were a pain too.
Walking through Madrid airport with $25,000 of legitimately earned pesetas in bills which could not be transferred to Britain through the banking system was far too exciting for my liking.
From a British merchant banker's point of view, it was thus very convenient when all the local foreigners converted to the same currency, rather than lots of different ones.
After that, you needed only two compartments in your wallet: one for British money and the other for foreign money. Then you could travel all over Europe without worrying about changing currencies.
It was a very 19th century feeling, almost as good as being back on the gold standard!