1. With the echonomic and human resourches they has they can develope whatever they want, and outcompete others easily with use of time.
If they throw their weight behind Bitcoin or an altcoin, whichever they choose will get a boost. If they start from scratch, they'll have the same problems all altcoins have, of getting anyone to care. The only way I can see it working is if their new coin is technically brilliant, and even then it's dubious. (Lots of altcoins seem technically better than Bitcoin to me, but they don't have much momentum.)
2. The mainstream people and market will adopt it more easily, just because it is branded and has a trust foundation even if it would be desentilized. Look at gmail from they started developing it and what it is today.
Although that's true, most of their own services are free. They can't get the ball rolling by accepting the currency themselves because most of us don't pay them anything. I think being endorsed by Amazon would be a bigger deal than being endorsed by Google.
Their resources could even count against them. We know they have huge server farms, so if their own coin is mineable by them, they could mount a 51% attack against it. It'd risk being treated as a private currency rather than a distributed one.
3. if they put focus on something they actually finish it to goal.
That's a big "if". They have a lot of internal projects that never see the light of day, and a lot of the ones that do are half-baked and/or get dropped. They are not above having two operating systems - Android and Chrome OS - in the same mobile space.
Overall, I think Google and companies like them are far more likely to endorse bitcoin than create their own altcoin.
