This has been a question I have come across many times, and must say, is not a pointless one. I have been asked this by my friends many times I discuss an idea with them, and Google told me that many VCs do it too.
I have always loved Google. For their culture, for the simple UI of their products, for supporting open technologies, for providing high-quality products (mostly) for free, unless you are a power user; and for tackling big problems. Theoretically, many of those things are still valid. But there is a problem. I am no longer a student, and when I pick a product, especially for professional use, I have to know that it will work, I will get the support in case I need it; and most importantly, it will still be around 6 months or 2 years from now. That is where this argument has started faltering lately.
I'm sure Google is not abandoning GMail anytime soon. But can I be certain about things like Blogger, Calendar, or Feedburner? Not with certainty, I suppose. They'll notify us in their Spring Cleaning updates and give time to export the data, but I still don't see why shouldn't I just stick to a company that is focused on that one product.
If you want to do something they are already doing, I think you should not let this fact be the sole deterrent, as long as you know there is a market and you know that you can provide a solid product and good support.