I can think of a lot of reasons why SD cards would be a great solution. Bur for a dedicated console, the cons far outweigh the pros. Firstly, a 64GB SD card today costs a little over $20 at retail and the high performance ones boast around 90MB/s transfer speeds. Now even if we say in 2020 those kinda cards get cheaper and consider OEM prices, then we are still looking at something that could cost around $10 for the card and packaging. 

Whereas, a BDXL disc capable of storing 128GB of data on one disc will cost them no more than $3 for the disc and packaging. Yes carts have a speed advantage as even a 8x BR drive peaks at about 36MB/s (which is why all games install to the HDD today). 

It just makes more sense unfortunately to stick with discs. As far as content distribution goes, outside of digital distrubution its flat out the best and most convenient way to get large chunks of data out there. 

When you really think of it, if Sony and MS could just do away with the disc drive in the console they would jump at it in a heartbeat. And eventually they would have to. All they have to do is figure out a way of conveying a message that says..... you can still use your discs as you would have, but the console doesn't come with a disc drive so you would have to buy a disc drive seperately. Supoorting external HDDs pretty much means they could also support external disc drives too.

Sounds fair enough. It will depend on 4k TV pricing and market growth. But, its a sensible prediction, especially for Pachter.

The next generational leap will be native 4k and the power and pricing of electronic components will probably drop enough by then to make all this possibe. 2020 or 2021 for sure.

Too much is made of 4k. It depends on what screen size you prefer. But I doubt on a smaller screen, 4k is noticeably better than fully anti-aliased downsampled 1080p.

Don't forget economies of scale and profitability. These consoles are not designed with maximum wankathon effects in mind - that's for the master race crowd. 

Game carts in mass production with more storage space, speed, and cost reduction, by 2020 could be a possibility, but more unlikely than discs, correct. A 4k BD drive definitely is the most likely for many reasons, even beyond gaming.

A separate discless sku, add on BD drive, or ext BD drive (if they push for ext SSD/HDD), are all possible for PS5, agreed. The future is a discless stock console, but thats a decade away anyway. Now is the time to start transitioning to get everyone on board slowly but surely as more and more people have fiber optic connections with higher and higher if not unlimited caps. For the hard core hard copy gamers, there will be an option for them, but what used to be the norm, will be an add on/extra in the distant future.