Think of the market for domain names. Would there be a similar market for serial codes? What I mean to ask is, can we own, coprwright, trademark etc. in anticipation of their use in the future?

In order to file for a trademark, you'll have to state the intended goods/services. Basically, you'll be telling the government what types of products and/or what types of services the mark will be on. So you cannot just file an open-ended application, it has to be specific.

Also, in order to register a trademark, you actually have to be conducting business. For the Federal trademark, that's in at least 2 states or between the US & any other country. For State trademarks, that's within that particular state.

So you can see, the trademark office has requirements to prevent the very scenario you're talking about. Now, you could file for a trademark (provided that it's legally available; comprehensive research will show you this) for a specific product and/or service and end up selling it to another party.

Hope that helps! I wish you much success & happiness in all your ventures!

Just an add on that trademarks aren't magic amulets granting one ABSOLUTE EXCLUSIVITY for what terms, symbols, etc. are "desired" to be granted such. You can file one for abc123 to sell T-shirts, but you can't stop me from using the same term to sell bowling balls UNRELATED TO YOUR USAGE.