The UPC agreement has already been ratified by eleven EU member states, including The Netherlands and Belgium. To allow the UPC to start, it is still needed that the United Kingdom and Germany ratify the Agreement.
The present announcement makes it highly likely that the UPC will become operational in 2017. Uncertainty remains about what will happen when the UK leaves the EU. If the UK cannot remain in the UPC, it may be necessary to move the branch office of the Central Division of the UPC away from London, to Italy for example.
The official press release of the UK government can be found here.