(Also, come on, it would be a trillion euro company.)
On the contrary, I think any company that grows that big would be split into smaller companies. This makes sense to me. 100x10b euro companies, or 20x50b (∆) euro companies provides a much higher social benefit than a single behemoth, even if it doesn't make the magical GDP number go exponential. Small companies can be controlled by legislation. Huge companies do the controlling, and that way lies dystopia. Trillion dollar companies are the American dream, not the European one.
(∆) Realistically it wouldn't divide that way of course. The value of the split companies won't equal to potential single huge company, they'll be either higher or lower.