Simply put, it will end up being litigated in court. It blatantly violates the Washington State Constitution’s single subject clause, so a legal basis for challenging it exists. Nowhere in the title or text of the measure on the ballot is scrapping light rail to Bellevue mentioned, yet (if allowed to stand unchallenged) it would most likely achieve that end. Based on the ballot measure that implemented the project, extending light rail to Bellevue has the support of both the majority in the Sound Transit district and the majority in Bellevue itself.
Therefore there exists both a means to challenge the measure in court and a motive (an electorate annoyed at falling for a bait-and-switch) to do same. And the absence of any mention of light rail in the measure will furnish ample evidence that the voters did not intend this outcome when they voted for it, which will probably cause any court-interpreted revision of the measure to gut the provisions of it which interfere with the proposed light rail line.
It may even get overturned by a subsequent bill in the legislature before it gets through court. Normally, the legislature is reluctant to touch the text of voter-approved laws, but again, the bait-and-switch nature of this one might bias the legislature in the opposite direction to the normal trend.
Moreover, the system listens to what Big Money has to say, and with the exception of Kemper Freeman, Jr., Big Money does not want I-1125 to pass. Transportation in the Puget Sound region is a horrible mess, this mess is making it hard for the Big Money crowd to do business, and the initiative will complicate the process of doing things to help relieve the transportation mess.
Naturally, when the inevitable happens, Eyman is going to go into conserva-victim mode and whine about how the evil courts and legislature are subverting popular will. Which will be something of a rich comment when one considers that the measure was obviously deliberately crafted to be a bait-and-switch. It’s not as of the single-subject clause is any big secret or anything: it’s right there in the state constitution, and Eyman’s initiatives have ended up being reinterpreted by the courts in the past because they’ve run afoul of it.
Of course, Eyman’s main motive in the thing is money. He earns it by hawking his services to the highest bidders in the right-wing crowd; he will laugh all the way to the bank no matter how much the legislature and the courts end up gutting the measure. Whether or not the thing eventually flies is completely beside the point.