I do feel that it's tougher challenge to put together another themed set that's as good as the last two years when you're focusing on an alt universe that doesn't exist yet and only the niche of Botcon set holders will ever know about. The past 2 years had underlying premises universal to the whole G1 concept.
To be honest, why can't they do the combiner teams, without the combining. Those would still be loved irrespective of the fact of wheter they combine. Teams like the Stunticons and Combaticons have range of figs they're existing designs could be based on as long as you change colour and head mould.