Heyya Rags,
You may have noticed that the Rune school has fewer spells than the other 2 schools (and even they only really go to L15).
"Watch this space" is, I guess the not-so-subtly-hidden-message-between-the-lines

We're currently concentrating on increasing the available Spell Schools, and should have a further 5 (yes FIVE) Schools available over the next couple of weeks.
As a token spoiler, the schools are:
1. Curses (Combat Magic, Negative Offensive)
2. Blessings (Combat Magic, Positive Defensive)
3. Illusion (Very, deeply, cool)
4. Scrying (Also very, deeply, cool)
5. Summoning (Also... )
We know what's in most of these schools, and we're largely just running through the balancing mechanisms at the moment. Better to get them right first time than upset everyone with the nerfbat later down the road.
Best,