When I became a Points member via an Ebay purchase of a week that the prior owner had already converted to RCI Points, I had 5 years remaining on my RCI Weeks account. They sent me a refund check for the 5 years membership fees, since the credit card originally used to purchase 10 years was no longer valid. Otherwise they would have refunded it back to the credit card.
Yes, you can just revert to owning the exact Unit number and week of the "underlying week" you have won. Just do not apply for an RCI Points account. Make sure to let the closing company know that this is your wish, otherwise they might go ahead and file the application on your behalf, although technically you are supposed to sign it.
If you plan to use your week every year, you do not have to join RCI at all--not even the Weeks program. You could do so at any later date if you decide you would like to exchange your week, and/or have access to RCI's Last Call or Extra Vacations inventory.
Unless you are interested in taking last minute vacations or traveling in off season, it may not be worth joining RCI just to access this inventory. If you have a friend or relative who has either an RCI Weeks or Points account, perhaps they will be willing to let you look at the inventory by logging onto their RCI on-line account. The excess inventory is the same in Weeks and Points.
It is my understanding, but please double-check this, that if you join RCI Points and decline to pay next year's annual fee when it comes due (or any year thereafter), your RCI Points account will be terminated and you will revert back to owning the fixed/deeded week you have just won. But once you leave RCI Points, you would have to pay several thousand dollars to "re-convert" your fixed week back to RCI Points.
One disadvantage to remaining in Points is that if you lock in your week and then decide to let a friend or family member use the week, you need to purchase a $59. guest certificate from RCI. I personally feel that's outrageous. It's your week, after all, and you should be able to let anyone use it. I'm also not sure if RCI prohibits you from renting out the week, the way they do if you obtain a week as an exchange. You need to check this out if you think you might want to do that.
If you join the Points program, you can call RCI 13 months before the scheduled check-in date and tell them you will be using your unit next year instead of receiving Points. You can change your mind in the following months and decide to deposit your week instead of using it, and then receive the Points. I forget what the exact time frame is and whether or not there is a fee to do so.
I have a friend who owns weeks at the same resort as I do. I use my week every year. She requests RCI Points instead. One time she saw availability at a prime resort that I have always wanted to stay at. She put the unit on hold and called me. I decided I would rather go there than to my own resort that year. So we did a conference call to RCI. The VC released the week from friend's account and was able to pick it up for me. At that Point I deposited my week, received my Points, and used the Points to confirm the coveted week. (I could have also borrowed Points from next year to accomplish the same thing).