If there is an unflappable reason why one person will never consider anything more than friendship, both persons know this early on, then sure.
At this point, "maybe under some condition" is not in the background, so it can't get in the way.

If it is in the background, no matter how well or long you are friends, the thought is free to present itself, and one party may decide to shift gears at some point in time.

For me it would be ideal that the other person had a type that I will never fit, that way I don't have to worry about accidentally flipping the lust/love switch.

If any type of attraction is possible for either side, then it can happen.