It hasn't happened yet, so don't think about it now
Nice. HAHAHA!
Tell me do you trade the bitcoins directly with the miners only and that too every time? I guess no.
Consider this what if there no gold left on the earth to be mined? The remaining one in circulation would still continue to change hands regardless.
Similarly, when no new coins are mined the remaining coins would keep on transferring from one person to another.
I think this is a wrong analogy. Bitcoin can't exist, or "change hands", without miners, while gold perfectly can. So, answering the question, we should rather concentrate on the motivation for miners to continue doing their job. And the motivation will always be there, as shown in the comments above.
I would agree with that, I mean how you can transfer bitcoin if there will be no miners and bitcoin isn't something tangible that you can just transfer by hand.
would that not make the buyer withdraw from taking step further based on the mentality that the limit has been exhausted?
I doubt that he couldn't get the logic not unless that person is new in crypto currency. Imagine if the last coin will be mined while the surge of demand is there, what could possibly happen? Simply, the law of supply and demand.
Bitcoin is not an altcoin that could be easily exhausted in the market.