I think you need to redefine your definition of a 'date'
A date is for spending time with someone, doing something that is fun for both of you, and getting to know each other better.
It is nothing more -- that is, it is not a 'lock' on any kind of more emotional or more physical relationship.
If you start getting into the mind game of
'well I won't make the effort to go out on a date with her because she would probably not be interested in [pick one: going steady, jumping in the sack, having my children] so why bother'
then you are setting yourself up for a long and lonely life. You simply cannot make people respond and behave according to your mental projection of how things should happen.
A date is just 2 people having a fun time. Period. Go on the date, drop all of the expectations, listen more than you talk, smile, be gracious and courteous, and most of all remind yourself how fortunate you are to be spending time with this other wonderful and interesting person.
Get this: Even if (unlikely) she never speaks to you again in your life, you still would have had a good time on that evening - so that is worth it - it's a winner no matter what happens in the future.
Also, if she gets the message that you are sincere and real, not pushing her into a relationship, and are truly interested in her as a person, she may become the best friend you ever had, or she *may* become the woman you marry and spend the rest of your life with. Or you may have some kind of relationship that blossoms, ends, and you each find other people. You never know. And you can't pre-plan that.