Hard call, yes if a joint totally lets go the steernig would be seriously affected. There is no way anyone can tell you on site just how far gone or loose your joint or joints are.

Chances the mechanic was either using the scare tactic to get your money. Or was saying what would eventually happen if the car remained in service. Again you need an experienced friend to look and estimate how loose they are. You are going to be hopping mad if they are in pretty good condition. Most likely there is some wear though.

Those joints are elegiable for change when even a little slop is present to maintain alignment. They can by the same token be almost falling apart. Or somewhere in between the two mentioned conditions. Someone has to have a look to determine reality. In a way there is a test you can do.

If you can get under there and grab the top part of the joint in one hand and the bottom in another.You should not have a lot of up and down movement by pushing and pulling. You can compare one joint to another to get the feel. If it goes up and down perhaps 1/16 inch I would drive on it. If it goes up and down say 1/4 inch it is too far gone or at least I would not drive on it.

Remember it is a ball in a cup. If wear is too much the ball can fall out of the cup. This is not a recommendation to do as I might. It is one of those judgement call things. Also far better than saying to yourself. Well I will just take a chance.

If he alllowed you to drive the car away from his garage remember without saying it was extremely dangerous to do so. Chances are the wear is not that great. But check yourself. With certain steering parts like this I never would suggest a person do something dangerous. Loss of steering while driving is about as bad a senario there is sometimes.

Another thing you might do is phone the mechanic and ask him how bad those joints on the centre link were and is it safe to still drive on them for a few days until I get them changed.

I really preffer the self examination as I have no ideal one way or another how honest or conciencious your mechanic is. It is basically just when wear is detected they should be changed sooner that later. He could be very competent for example but far too expensive for your tastes. Just charging what they think the market wll bear. I know the last statement sounds contradictory yet in many ways it is the reality of the times.