I'm sure that EB/Gamestop and other stores that deal in new and used games will protest, but MS and Sony simply won't care. They only care about NEW game sales and gamers always have plenty of options. The prices are fixed as well, so other than pre-ordering at Gamestop or similar stores, they'll pay the same at Walmart, Best Buy, and so on.
I know that personally if this were to happen, my son would be pretty disappointed ! Other than Christmas where he gets new games as gifts, we always buy used (and he's 100% okay with it too).
Again this is just a rumor. Everyone should relax until we know if it is actually true.
And not to sound like a jerk but you are right. They don't want the used games customers. New consoles are typically sold at a loss especially at the beginning. Sony and Microsoft get a licensing fee for each game sold. Eventually you buy enough games that they make their money back and start making profit off you.
When you buy used they get no licensing fee. They are almost better off not having the used game only gamers as customers. They lose money on the console sale to these people and they don't make it back let alone make a profit because they don't buy anything new. They probably wouldn't care one bit if all the people who only buy used games decide to boycott their consoles.
That being said... I say they should let the market handle this. If they copied steam and offered every game day 1 in downloadable form at a discount with steam style sales every now and then people would gradually shift to buying their games that way. They could cut out the retail middle man and lower prices. They would sell new copies at an average lower price but less people would buy used so they would come out ahead. The customer gets a lower price for downloading a game they can't sell and they get more money by not sharing with a retailer as well as reducing used sales that they don't see a cent from.
I'm not saying to do away with physical copies for those that want them but if every system came with a minimum 500GB hard drive and they made their online marketplaces competitive like steam does more people would buy online. Downloaded games should never cost more than the physical version. Unfortunately Sony and Microsoft are currently too slow to reduce prices in their stores and that is often the case. People are willing to sacrifice some of their digital rights for convenience and cheaper prices.
I don't personally buy used games because I want the people who develop games I like to make more games I like. I want my money to go to the people who created the game not GameStop. Also, like I said in the PS4 thread, you can usually beat GameStop's used prices with new games through other retailers like Amazon. However, I don't think they should block used games. Build a better online store and let the market stop them.