Google page ranking/position???

I'm doing some updates for a client who has a couple of links on Google ranked 1 and 3 for a specific search term. Unfortunately the link to the pages contains a specifc brand name, which the client no longer supports, and wants all references to it removed from their website and replaced with another similar product.

I know I can use the htaccess file to redirect the old link to the new link and I've suggested not having any brand name in the link in case they want to revise the product again in a couple of years. However if I use in the htaccess file:

Redirect 301 /brand_name https://domainname.com/new_product_name/

Then will the high ranking links listed in Google be dropped over time or is Google clever enough to realise the old link has been moved and maintain the high ranking to the new link. Also will it update the description associated with the Google listing for the new product description as that is different to the old one or is it a matter of starting over from scratch and building up the listing from afresh and getting the old link delisted.

Any thoughts as I really havent had to deal with this particular issue in the past. I guess most of my clients have a relaxed attitude.

Cheers

Os.