No, U2 isn't going to get out of their contracts with LN and TM, nor do I have any reason to believe that they want to. However, they could require certain accommodations. For example, they could have demanded that every fan club member get a code to be eligible to try for tickets (as it has been in the past few presales) or require that extra customer support agents be available to more promptly resolve the issues that will arise.
Now that the presale has turned out to be so massively frustrating for many (maybe most) fans, U2 could go to LN and TM and require that codes be released to all fan club members who didn't get them in the first round so they have a chance at getting tickets for the additional dates that I am guessing will soon be added to the tour. (For the i+e tour, they had eight shows at Madison Square Garden and had a packed house every night, compared to only one currently scheduled for the e+i tour. I'm sure there's still plenty of demand out there.)
U2 has been a huge cash cow for LiveNation and Ticketmaster, so the company will likely be motivated to keep the band happy so they renew those contracts in 2020 (just in time for what will hopefully be a 30th anniversary tour for Achtung Baby the following year!). U2 should use some of that clout on behalf of their fans.