1) Continue to publish 4e as is and plan (not design!) 5e.
2) Get some serious customer data: age spread, age of entry to the hobby, modes of playing (p&p groups, con men, playing online, only reading and/or collecting), buying habits.
3) Try to calculate expectation values: mean time of playing till leaving the hobby, spending mode (once only, peaked, continuous), valuable product segments.
4) Plan for different publishing models: classic book publishing, book publishing plus electronic services, electronic services plus a bit of book publishing.
5) Examine probability of completely different future technical solutions being available and somewhat wide spread in the next decade: VR, augmented reality, 3D printing, ...
6) Analyse these data to construct several different business models for 5e.
7) Decide for one of these models and start drafting a viral marketing campaign aimed at the future audience, completely neglecting the existing customer base.
8) Make plans for the marketing the new publishing model to the existing DDI customer base.
9) Draft the speech for the upcoming "CEO of the Year" ceremony.
10) Re-publish all products at least 30 years old in huge, senior-friendly font and/or audio books.