Interesting read. Its understandable that for space shuttle, the kind of material needed would be light weight with low thermal conductivity, and this one fits perfectly into it. Ceramics are a tad too heavy to be used as furnace linings. If this material could be made a bit more stable for long term, we could see even everyday equipments requiring high temperatures being made of this.
Are there alternatives
I even doubt if the conventional ceramics will suffice apart from its weight. The ability to withstand two different extreme temperature may send a ceramic cracking and go brittle.
I have no idea if they use the material for any other use, given its current cost.