mary I can answer that one, the 'what did Remainers think or want the EU to be like in 10-15 years?'
We wanted what we had. A dynamic, responsive, legally and economically bound together group in the service of all its citizens.
It would always ebb and flow; it would not have been without controversy. Mistakes will be made.
We expected it to keep war from our doors. We expected it to stand up to bullying from other big powers, like Russia, China, the USA.
We recognised that it came with sacrifices. Because successful partnerships are not just me, me, me.
We wanted the international cooperation that membership of such a powerful block facilitated. We wanted our best minds to be able to cooperate with other great minds, including those from outside the block (via international cooperation with big, well funded research and scientific EU foundations).
We wanted what we had.
Yes, it's not perfect. But we could reform it as a 'punching-above-its-weight member'. But nope. We've taken our football and gone home.
The one, tiny comfort I take is that our departure may reform some of the sillies of the EU. One we will beg to rejoin.
But with the clout of Romania.