There is still an issue however with us and being eligible to play in Europe under the current set up. However thats something that isn't important at this moment.
As for Rangers/Celtic/Any other Scottish club playing in the pyramid, yeah it's a question of where they enter most of the people I have heard think its a god given right that they should go straight in at the top, or at worst the championship. Not sure if you wouldn't be welcome and if the logistic thing would be an issue. Swansea to Newcastle is about the same as Swansea to Glasgow.