When Andy Rubin, Google‘s Corporate Developer honcho, said that the company’s acquisition of Motorola‘s Mobility Division was about “protecting the ecosystem, and extending it as well,” many writers focused on the first part of that comment. There’s no doubt Google wants to shield Android, not to mention benefit from Moto’s 17,000+ patents.

But let’s not be too quick to overlook the second part of the statement. Now what do you suppose “extending” might mean? There’s no way to know for sure without a crystal ball, but let’s play around with that for a second.

Google stunned the industry when it announced it was scooping up the Android manufacturer, who — despite its very successful Droid line — still hasn’t managed to best its competitors. (In recent years, Moto’s market share just hasn’t been able to bust out of the single digit bracket. According to IDC, its worldwide smartphone shipments are getting trumped by Samsung and HTC.) In other words, Mountain View saw an opportunity and, despite being in a totally different end of the mobile realm, swooped in to grab the Moto division anyway, cementing the idea that nothing is truly outside Google’s purview.

Now, I know Google co-founder Larry Page said Moto would remain an independent entity, but I figure it’s probably to ease the minds of other Android makers who are likely concerned about the company throwing its weight behind one OEM right now. But we’ve all seen focus and priorities shift over time. There’s little reason to believe it couldn’t happen here, and if it does, it would open up a world of possibilities. After all, if these two crazy kids could get together, what’s to stop Google from exploring yet another left-field acquisition?

So let’s think for a second — what other company has a strong brand identity and recognition, but has failed to grab a strong foothold in its market? That is an Android supporter, but might be bracing for tough times, making it ripe for the picking?

Try this on: What about Sprint? As America’s #3 carrier, it has the most to lose if the country’s #2 and #4 carriers become one. Verizon‘s the top dog on this block, and so has been basically shrugging off the AT&T/T-Mobile merger, leaving the “Now Network” out on a limb alone to rail against the deal.

But if Sprint and Google joined forces, it would send a ripple wave that would rock the mobile industry. And it has far more potential now that Motorola will be secured, since it would make a comprehensive Android environment possible, with every piece of the puzzle — software, hardware and network — brought under one roof.

Couldn’t you see it? All the vertical components would be in place for a total end-to-end solution, with a fleet of Androids — designed by Google, made by Motorola, launched on Sprint — orchestrated seamlessly under the auspices of a single overseer. How tempting would that be for you, the end user, to know that you could have the most advanced Android hardware that would always get the software updates first, that would have unlimited data and 4G compatibility? That would be something even Apple couldn’t match.

Before you say this is a crazy notion, remember that we’re talking about a company that loves experimentation. It has not only redefined search engines, email, calendaring and cloud computing, but threw itself boldly into the smartphone OS game to challenge the iPhone. It even attempted to defy our stagnant cell phone subsidy structure by selling smartphones directly to consumers. If nothing else, Google has demonstrated again and again that it’s not afraid to challenge the status quo.

What do you think? If Google’s not seriously considering running Motorola and adding Sprint, do you think it ought to? Or would that be a bad move, considering it would probably upset HTC and Samsung? Tell me if this theory strikes you as crazy or brilliant in the comments below.