Manufacturers love it. Inkjet printers, coffee makers, cars, vacuum cleaners, laptops. If a manufacturer thinks it can get away with monopolising parts, accessories, and services it will try it.
If Epic does win it could set a very wide-reaching precedent.
On the flip side, the fact that no one has successfully sued manufacturers of inkjet printers, coffee makers, cars, vacuum cleaners, and laptops over this issue should give you some clues as to how likely it is for Epic to win their case.
Philips tried to block other companies from making Senseo-compatible coffee pads. The European Patent Office revoked Philips' patent after opposition of competitors:
And actually in the case of Inkjet printers, the court of appeals and the supreme court ruled in favor of companies making third-party cartridges and refills:
Retaliation, such as this one by Apple, or the recent kerfuffle around the WordPress app are only going to increase the probability of antitrust action against Apple.
The EU cases aren't likely to inform how Epic's case is going to work out in a US court. The European Commission also just lost a lawsuit against Apple so just because they take an aggressive position doesn't mean it will hold up in court.
The Lexmark case was about whether patents right end once a patented product is sold and doesn't seem to be directly applicable here. But note that Lexmark's technological and contractual "post sale" restrictions preventing the reuse of discount toner cartridges were not considered illegal, even if their patent rights were considered exhausted after the sale.
The lawsuit doesn’t have to succeed in court for Epic to succeed. If the case generates enough publicity but ultimately fails, they may be able to lobby Congress for a new law akin to the Magnuson–Moss Warranty Act [1]. Then, instead of precedent they might have statutory protection for what they want to do.
If Epic does win it could set a very wide-reaching precedent.