One can treat an EWP (p. strobus) like a JBP - they will reflush and produce short needles. I am not suggesting that you change what you are doing, as JBP treatment will lead to trouble because EWP doesn't back bud onto old (needle free) wood - just some horticultural trivia that might be helpful to your figuring out your way of handling the species.
I have no experience with Austrian black pine. They might react similar, but since i have no experience i would not remove all of the old needles. I would leave 6 to 8 pairs of last years needles. If the tree is strong there should be good reaction. When roots and health are good, there is no reason why a pine would be killed.
i have no real plan for the tree yet just watching and observing.
but I think its somewhere in here. 
Eventually when you want the foliage close to the trunk you will have to cut back to the side branches. Most often this is done in fall. The problem with cutting back all the foliage to side branches is that you will eliminate lots of the foliage. There are two options for the tree, it will trow massive backbudding or it will backbud, but slowly. When the tree wants to take it slow it will take 2 or 3 years for the pine to start the turbo again. Keep in mind that the more foliage it has, the more roots it will sustain and the more power it will have to grow / backbud. For this year i would cut back the new growth (it looks healthy). Leave 6 pairs of new needles. Leave 6 pairs of old needles, this is a conservative approach. Style the tree in fall. Since clever branch placement works a lot faster than backbudding try to envision several designs. One with backbudding (your perfect tree with foliage close to the trunk). And one design you can use the branches as is. This last design is often one or two branches that can make a more compact design with lesser foliage. This fall you will make the movements in the branches, it is the most important styling. Wire accurately with big wire and make sure the angles where the branch originates from the trunk are nice. Your tree has a nice trunk but a lot of "problem branches". For the first styling keep as much branches and foliage as possible.
Had to look up the OCD stuff. Thanks for the thumbs up. We are all here to learn something. I share what i learned this far. There might people jump in that have ideas or tricks getting it faster or better.
Thanks for the answer. I was thinking the same, leaving the old needles to help the tree strengthen, but I wanted to check if that's correct or no.
