I can think of a few ways it could go, but I don't think either of them are at all likely

1) The writers start to make her character more jealous and paranoid with Tyrion's marriage to Sansa which will make her eventual betrayal seem more logical.

2) Tywin will find out about Tyrion and Shae and will pressure her into testifying against Tyrion in exchange for her safety, and then execute her anyways, which will be what spurs Tyrion to kill him, supplanting the Tysha subplot from the book.

Those are my theories at least, but they both contain some pretty hefty flaws.