Ideas abound. And so do scripts, treatments, synopsis's, scribbles, etc. The challenge then and now has always been two fold (not true, but I like 2's). Although, technology, access and credit cards make it a bit less strenuous at a certain threshold.
A) The resources = Money, equipment, talent, time, etc.
B) The "Why's". Why do you want to invest the A's for the B's? Be specific. Search for the answer to the question, because this clears the clutter. And, then you can judge whether the A is really worth the B for a particular project.
We can never predict the future. You can write a 5 year, 10 year, 1 month, 7 month plan all you want. And, I'll be the first to encourage it. But, the world probably has other plans.
You roll with it. Don't put all your faith on a "singular" preconceived plan, one that is destined to change. That's what life is. One continuous ocean of swirls and currents and big FUCKING WHALES AND GIANT SQUIDS.