I haven't ever seen a decaffeinated lapsang souchong or Russian caravan tea.
Lapsang Souchong's aroma is more from the smoke than the tea, in my opinion. It is made over pine smoke. The tea itself has a very smooth flavor and isn't particularly strong.
I suspect that if one took a smoother herbal tea, and put it through the same process used to produce Lapsang Souchong, the results could be quite good. For example, a pine-smoked rooibos. If one desired a tea flavor, one could blend a pine-smoked herbal tea with decaffeinated black tea, producing a russian-caravan-like blend.
Perhaps this is an unexploited niche for a creative tea manufacturer!