The deposit for a Signature reservation in Europe is no longer an option at https://www.teslamotors.com/own#/model-x. The option to upgrade my regular reservation was not removed. I tried to click on the Upgrade and Tesla is now waiting for my deposit of another 230,000 SEK... Guess the upgrade-option will be removed soon.
The reservation of Signature for North America was closed in March already. Probably Tesla have got all Signature reservation they have planned for. 1,405 have reserved Signature in North America and about 576 in Europe. Some more reservations in Europe might drop in while the upgrade from General Production is still open.