If this is correct then I would expect to see the EF catalogue either severely reduced or only keeping remaining stock in-country. If you want a EF lens, look for specials and take advantage of it while you can. The push for "full" RF range is on but there will still be gaps if the current EF lenses are all discontinued!
Let me just say that, with all the EF lens being around for so many years, buying now a brand new EF lens wouldn't be a great purchase from a cost/benefits point of view...on the used market you find them for 50% to 80% less, and there would be even more sold by people when RF gaps will be closed.
Example (it's not a RF gap, but I can compare as I acquired it exactly 12 months ago), buying an EF 24-70 f2.8 II today is
2.140€ price list on canon website, and between 1.500€ and 1800€ buying from any reputable retail shop.
I paid for it 610€ shipped (in summer you make super good deals on open auctions on eBay!)...so I would not fear reduction of catalogues, out of stock etc, EF lenses will be available for years, or decades, pretty everywhere on used market. Of course they would not get serviced after a certain period (in Europe, if I recall correctly, spare parts must be available at least up to 10 years after discontinuing a product), but if they discontinue the 24-70 today, the service will stop at the same time, regardless if it was bought used or new.
So I wouldn't personally worry about EF discontinuation, I would just consider all EF's as entirely discontinued starting from the day of the last lens was presented, which is
2018 according to Camera Museum.
...new lenses?! C'mon, let's get me my RF 50 f1.4 and finally make me happy ahah!
(...sadly, having just sold the 50 Art for the 40 Art, if they really present it, which I'm sure will NOT happen, I'm not going to buy it...and so they probably will really present it, just to slap me in the face!)