More adventures from WotC would be welcome. More good adventures from WotC would be even more welcome.
But for D&D to survive, never mind for it to be a success, it needs to make money, and lots of it.
To that end, WotC should:
- Sell PHBs (or, if they go for a single Core Rulebook, sell CRs)
- Sell DDI subscriptions.
And, where there's a conflict between the two, DDI subscriptions win. Somewhere, there are 'magic numbers' for DDI subscriptions - sell X thousands and D&D gets to survive; sell Y thousands and D&D gets extra investment; sell Z thousands and we get a new cartoon series.
(Potentially, there's also #3 - sell Fortune Cards. However, I'm ignoring those in the hope that they'll go away.)
Everything else is worth doing if and only if it results in greater sales of PHBs or greater numbers of DDI subscriptions. Even measures that increase the number of players only matter insofar as they lead to greater numbers of customers.
(The reality is that the majority of D&D players, if they buy anything at all, buy exactly one item: the PHB. A smaller, but still significant group, buy a second item, being a splatbook for their chosen class. Beyond that, you're selling to the tiny percentage of hardcore collectors who pick up just about everything. That's why most products get a single, modest print run... and are then easily available, new, years after publication. Even worse - with 4e a portion of splatbook-buyers bought a DDI subscription instead, canibalising sales of what should have been the best-selling supplements. So now, even those previously-reliable splatbooks have become marginally-worthwhile products.)