Google can use Motorola to force the issues that have plagued Android for a while. Motorola devices will probably become "pure Android" devices like the Nexus series, pushing carriers to abandon the crapware and carrier-specific UIs they're infatuated with.
Most people I know with Motorola Android devices say the build quality is for crap. I hope Google can improve this, but if not, I hope they can at least get the carriers to quit layering garbage on HTC's nice hardware.