I'm sorry too that you are in this situation. I have been in situations that were similar. Closed my area and lay offs. Turned out for the better, though I didn't realize that when it was happening.
As I read your post I was seeing alot of positive angles and thought of ideas on how to deal with it. Can't help it, I love to make lemonaide when life hands me lemons.
You are a certified gastroenterology RN!!! This gives you bargaining power imo. You have certification!!! Those docs are going to want you! Especially if you already have a good relationship with those docs. If you like working with them and it seems you do since you already work with them.....no fear of not knowing who you'll be working for!
The retirement fund: Can you roll it over into the new plan? Can you negotiate to have any of the hospitals portion of your money rolled into it too? Or how about a cash payout on that money and then put it into bonds?
Working in that clinic might be better than you think! Great hours and you'll be working with people you already work with! Docs in that setting reley on the nurses very heavily and I've seen nurses do very well, monetarily, the docs might just treat you better than you have ever been treated before! Demand better PTO, vacation time, retirement bene's, etc. Or at least comparable. Here's your chance to negotiate and bargain for the pay and everything else you want. Go get it!!!
I doubt the clinic will have you feeling like you are on an assembly line. Have you ever worked in a clinic before? You are already specialized, so you know what it's like to work in an environment that is perhaps not as varied as others. Clinics can be wonderful environments to work in! Sure, you'll have specific responsabilities, but to me, that is a plus....to know what is expected of you.
Your right to worry about your age and working in the hospital on the floors. Could you do it till you retire? I know I can't. Here is your opportunity to continue to know that you'll have a job that you can work for until the day comes where you can hang your nursing cap, once and for all, and bask in your retirement.
Lastly, the hospital, if you feel that they are selling you out, why do you still want to work for them??? Up theres! Geesh, they are going to loose you! Isn't there a shortage of hospital nurses? Secretly, maybe they don't really want you to go at all but have an agreement with the docs to supply those GI nurses to the clinic. I'd bet they do. Is there an undertone of this happening? Are the supers asking you to stay with them? Are any of your bosses painting this as a bad picture if you went to the clinic? Just curious cause if they are, they don't really want you to go to the clinic.
This could be youir opportunity of a life time! Life is what you make it! I vote for you embracing this new opportunity and go have some fun working for the docs at the clinic!