We've now got a look at the 7-day Test of the Thronebreaker if you subscribe to the summoner sigil.
I took a look at Cav rewards vs Thronebreaker rewards, and yes, they are improved, but in my humble opinion, it's rather minimal.
Units, gold, health pots, energy refills, and number of 5* sig stones are unchanged.
Generic ISO improves from 33,000 to 50,000. FYI Kabam, that additional 17k ISO isn't enough for a single level up to a 6*, which is likely the target rank up for anyone with a TB title.
5* shards decrease from 1,000 as a Cav to 500 as a Thronebreaker.
6* shards increase from 0 to 400.
The 6* shards is a welcome addition obviously, but overall, not much changed. At the risk of sounding greedy, I think you could have done a bit better Kabam. Add some 6* sig stones, or at a minimum, increase the number of 5* sig stones.