This would be an unhinged move; essentially deleting domains for political reasons. Any business doing due-diligence would be forced to move from their .eu domain.
Of course, they can still move to remain in the EU after all.
The EU is actually quite efficient with its money considering all the things it does. Probably because loads of things are done centrally instead of repeated across 27 countries. This despite the stupid continuous moving between Brussels and Strasbourg.
According to http://ec.europa.eu/budget/explained/myths/myths_en.cfm, the admin overhead for the budget is about 6%. Amount of people for admin is about 70k. That's nothing if you compare it to any big city, let alone to a country.
The examples provided on your link are Galileo, business investment and huamnitarian crises, terrorism and security threats. To be honest, these aren't very good examples from my understanding.
With Galileo, I'm not sure why leaving it to the ESA exclusively instead of this shared setup with the EU is better or more 'efficient'.
For business investments, the EU has caused some of the very problems they are "investing in", including making farmers and fisheries dependent on grants to operate or just go out of business. The imposed VAT rates and conditions cause less spending that lead to very situations that require this to start up in such an environment. With more self autonomy, governments could look to more effectively focus on industries that are more effective for their geography and avoid much of the red tape that prevents these industries from being viable. This does not seem efficient to me.
EU's recent history on humantarian, crises and threats has shown it is lacking significantly.
Let's take Greece for example, if Greece were operating independently, it would have been allowed to withdraw from the Euro (which it was prevented from doing so), moving to it's own currency and then devalue it's currency over the period of some years which would increase external investment into the country, floating the country's economy and returning it's economy to normality, not unlike other countries that suffered a financial crisis not too long ago, such as Iceland. Instead, they are just funding Greece with no working plan for recovery, while driving other countries into debt to support it. This does not seem efficient to me.
The EU completely failed to manage and appropriately deal with the refugee crisis and economic migrant crisis on the EU level despite it being there. It was a significant waste of money and then, to further the pain, it tried to take the work off it self by paying Turkey to deal with it; which is now blackmailing the EU into providing further funds. This is not efficient and I think the ECHR should really get more involved in this matter.
Regarding threats, the EU gave a lot of promises and love to Ukraine, annoyed the Russian bear which now occupies half the country.
> the admin overhead for the budget is about 6%
I'm not seeing the value in return, sorry.