Baba Metzia 48a - Difference between R' Yochanan and Reish Lakish

Rashi suggests that the nafka mina between r' yochanan and reish lakish whether money effectuates the kinyan m'doraysa is kidushei isha. It is not entirely clear from rashi whether he is speaking about the money that was used to pay for the object or speaking about the object itself. Regarding the money that was used to pay for the object, Tosafos 43a already established (in the end) that according to r' yochanan the seller may use the money as soon as he receives it and therefore can be mekadesh an isha with it, whereas reish lakish will say that the money cannot be used by the seller until the transaction is completed through meshicha. However, Rashi using singular rather than plural language implies that we aren't speaking about the money, rather about the object that was purchased with the money. According to R' Yochanan the buyer may use the object to be mekadesh an isha, whereas according to reish lakish the kiddushei isha wouldn't be binding until the buyer does meshicha.

R' Moshe Feinstein (dibros hea'rah 31) asks that according to the simple understanding of rashi that we are speaking about a case where the buyer uses the object that he purchased with kesef WITHOUT meshicha to be mekadesh a woman - how exactly does the buyer have the object in his possession to be mekadesh a woman without doing meshicha on the object? He suggests that the case to which rashi is speaking is when the buyer is mekadesh the object that he purchased using kinyan kesef and still in the possession of the seller, but is able to be makneh it to the woman via kinyan agav (which rashi in gittin 77b holds that it works by gett - unlike the Ran), or through a kinyan sudar. This is actually a chiddush that although she would be giving the sudar to him to acquire the object, it can work as kiddushin.

Another issue is the question raised by the ritva. How can the kiddushin be binding when the buyer is mekadesh an isha with the object since the seller still has the right to retract on the transaction. R' Moshe explains that the case would be where the buyer purchases the object using a kinyan kesef, then is mekadesh an isha using kinyan sudar or agav, and then does meshicha on the object which would retroactively make the original kinyan kesef used to purchase the object go into effect. Based on this, R' Yochanan who holds that we uproot kinyan kesef and implement meshicha doesn't mean that kesef is worthless, but rather the kinyan kesef is pending. When it is completed through a meshicha which prevents the seller from retracting, the kinyan kesef is considered to effectuate the transaction retroactively.

R' Moshe seems to assume that the kinyan kesef doesn't take effect until the meshicha and then goes into effect retroactively. But to me it seems meduyak from rashi on 46b and 47b that chazal didn't uproot the kinyan kesef. Rather, they allowed the seller and perhaps even the buyer to change their mind. But if they would decide not to change their mind the kinyan kesef will be binding. For example, if there was a kinyan kesef and the seller dies, the kinyan kesef of the buyer would be binding since there is no one to retract on the kinyan (i am assuming that the yoreish can't retract, but if he can we can always make the case by a ger who has not yorshim to retract).