A couple of points from Renzi's speech could be interesting from David Cameron's perspective. He said:
"Europe without the UK would not just be less rich. It would be less Europe, less itself."On top of this short bit specifically devoted to the UK's situation, Renzi also spoke of the need to achieve a "smart Europe" and of the importance of making EU institutions "simple". He also stressed how badly the EU needs to boost its economic competitiveness, because "the rest of the world is [currently] running twice as fast as Europe."
"We will do everything [...] to affirm that these values of investing on a different Europe need to be brought together to unity."
"Different ideas are a positive thing that make us proud, [they do] not irritate us."
The challenge here, for Cameron as much as the Italian Prime Minister, is to reconcile Renzi's vision of a 'United States of Europe' with his professed desire to keep the UK in the EU. His predecessor, Enrico Letta, spoke about EU treaty changes designed to settle UK concerns.
It is progress, of sorts, that EU leaders are able to identify the issue. However, now there needs to be progress on finding solutions that work for everyone.