Could I become proficient in say a year with ample dedication or am I dreaming?

A year sounds unrealistic if you keep your current job. If you treat programming like a job, and give it full time hours, and additionally study on weekend, then yeah, in a year you can be ready.

Now, whether that's 90k ready is another story.

If you're going to keep your current job, it could easily take longer. 2 years wouldn't be unreasonable to expect.

It really comes down to if you can take time off to focus, or if you can take a pay cut to transition to a new field. If you need to go directly from 90k nurse to 90k+ programmer, then expect a few years where you spend multiple hours every day after your job learning programming.

Think about a more traditional approach and the time involved there. 4 year degree and internships, then getting a good job which might pay 90k+ heavily depending on what you can prove you know and location. What you're asking to do is cut out anything extraneous and do all that in a single year without any work experience, relying only on interview skills and portfolio.

So yeah, you can do it, but it depends what you are willing to do to achieve it. Age isn't the limiting factor don't worry.

Now, once you have a couple years in whatever first job, it'll be vastly easier to surpass 90k. A couple job changes and promotions from there, and you can have more than doubled your current salary. What you should weigh, is if all that work and job switching is worth trying, given your planned retirement age. If you quit to learn programming, then you're losing 90k each year until you get a job. If you then get your first job and it pays under 90k, that's more potential money lost. Basically you need to make more than that for a certain number of years to make up lost salary, so that you don't set back your retirement, but instead get there faster.