AM3+ is not outdated.

The only thing related to AM3+ platforms, which can be considered as outdated is the chipset.

A quad channel memory controller would give no performance benefit over a dual channel controller.
Currently the bandwidth provided by a dual channel DDR-1866 (29.856GB/s) is not even fully saturated in most cases on AM3+ parts.
The performance benefit from DDR-2133 or higher can be seen in synthetic benchmarks only.

With the given, limited resources AMD should put all of their eggs in a single basket: A basket which says APU/SoC on it.
APUs / SoCs are the future in any case, there is just no way around it.

In case there would have been real demand for higher performance CPUs, we would been using a 10-core Komodos instead of 8-core Visheras. Komodo had 5 Piledriver based CUs in a single node and it would have been available for AM3+, C32 and G34 sockets.
It already existed as "release candidate" steppings before it was terminated and replaced by a cut-down version (4 CU) called as Vishera.

With the burder of the troubled manufacturing process lifted off things might escalate quicker than expected.

The APUs & SoCs are more complex than anything else the industry has ever seen.
A single chip CPUs have existed for 42 years now, while APUs / SoCs are around 37 years younger
It has taken and still will require time and chip generations before they can fully close the gap.
Ultimately APUs / SoCs will fully replace the CPUs.

"Resistance is futile"