Again, unless it is suggested, there is nothing wrong with that plant. If it's not broke don't try to fix it. If you do decide to do something drastic and chop it up or something, you'll find the cuttings root fine. That is absolutely how older plants look, just look on Google and you'll see a few examples, including the Wikipedia article. If the sceletium starts to rot the whole affected area turns to true mush quickly, it's how the plant is fermented in fact, but this drying as you call it is normal. Wluld you be concerned if a small tree started to "dry" and then hard when it's getting larger and becoming lignified? It can gets its "sap" too.
Tl;Dr, don't fix what isn't broken. If I'm wrong and it dies I'll send you another one if in the states