Company is moving. Need to decide whether to stick it out until the end (retention bonus and severance) or leave early (new job at likely more money).

My employer has decided to move the portion of its operations that include me to another state. While they would be happy to have me move to the other state (at their expense), they will give me a severance package if I decide to stay. I can keep my current job through Jan 1st, 2018 at which time I will be terminated and the severance pay will kick in for 2.5 months.

In addition to the severance pay, they will pay me roughly 15% of my annual salary as a retention bonus for sticking it out to the bitter end. If I don't stay until Jan 1st, I get nothing.

The thing is that the type of work I do (data analysis and data engineering) is currently in high demand. I'm reasonably certain that when I secure a new job, I will be offered 15% or more above my current salary. I may also get a signing bonus.

My question to you. Does it make sense to get a new job as soon as possible or is it better to stick it out until the severance kicks in next year?