At this point, there are two results from the previous step.

1) There is available 'real estate' using your desired keywords. Go to the next step.

Or

2) You have a decision to make. If all the above-the-fold content is sponsored advertising or authority sites you have a choice:

A) Go back and find more keywords, noting your competition before moving to the next step.
B) Throw in the towel and move to your next niche idea. (I do not recommend this, but hey, this is your business, not mine).

Now is the point where I talk about LSI (Latent Semantic Indexing). Google loves real content from real people. Just because there is very little real estate available doesn't mean you can't win the war with big authority sites. It will be more difficult, for sure, but it is winnable. You have to be prepared to work harder to gain that ground. Your secret weapon is LSI. By creating great content with ALL of the long-tail keywords that you have generated (I'd do this through five iterations (25 keywords total), you may be able to punch through to the top.