Blockchain wouldn't appear without Bitcoin. It would be nothing more than a very obscure programming pattern barely used anywhere, and the only people who know about it would be some guys from stackoverflow. It only exists as we know because of the huge marketing campaign created by altcoins and blockchain companies that tried to sell it as the next big thing.
The code behind it isn't obscure. The concept is what matters, the code really doesn't. If you want to dabble in it, you have to have some degree of technical competency. Even to this day, most people either have zero understanding or some misconceptions about how it works. The fact that it was conceptualized so early basically means it would've been developed with or without Bitcoin, sooner or later. Whether it gets any adoption is an entirely separate issue, considering the cost of implementing it, it probably isn't very great for the companies without all the PR. Cryptocurrencies popularized the idea of it and companies are jumping on the hypechain, that's all.
Obviously, there would be no way to tell whether my statement is true or not.