Politicians occasionally like to talk about the idea, but realistically it seems unlikely as it would requirefoolingconvincing Brussels to provide crapload of money for it.
the tunnel will be definitely be built in the first half of the 21st century as the shipping route from Asia to Europe is way shorter if using the Arctic route and it has less ice on a yearly basis thus every year the shipping routes can be used for an even longer period of time. The issue at the Suez canal has strengthened the trend of using alternative shipping routes and bringing production closer to customers.
In the context of Rail Baltica and the tunnel which will be built before 2050: The North sea is not a good place for container ships because the conditions can be very rough so realistically the cargo from Asia will be offloaded in Northern Scandinavia and sent into Europe by rail using the future route through Finland, Estonia and the Baltic nations.