Generally speaking, I wouldn't worry about it.
The chances of an overwhelming meteoric success are incredibly low. Even those 10% of startups that do succeed eventually, do it far more slowly than the legends and the movies would let us believe. And if you're working alone, then your chances of success are even slimmer, and significantly so.
In any case, looking for potential partners now to join you in some unspecified future is largely pointless. Do you really believe they will sit quietly and wait for you to succeed? By the time you might need them they will probably have moved on, being too busy with something else. Even if not, they can change their mind, no matter what they've signed. You might even lose contact with them altogether. It happens.
And finally, if you do somehow have a meteoric success, why would you need someone else? Having too much success? Well, looks like you're doing just fine on your own, so why not keep it up?
That being said, you do need to be prepared psychologically for a huge success. The first time I ran a marketing campaign that unexpectedly went insanely viral, I nearly went insane myself out of happiness. And I don't mean it as a figure of speech. Fortunately, it was a very short-lived success (about a week), or who knows how it could have ended. But at least now I'm mentally prepared for success. I hope. Such an exercise, an unexpected but controlled short-lived success, might be a good idea for most entrepreneurs, I think.