Here's my take:
- Determine the cost of storage for your entire collection. E.g., call three storage facilities and get the lowest quote for the total cubic feet you need to store. Hold this number aside.
- Keep whatever pieces hold even an iota of sentimental value for you. If these are just a handful, a relative, a train friend, or any number of people here would hold them for you.
- Sell the rest. Put the money from the sale into an interest-bearing bank account segregated from your other accounts.
- Each month thereafter, while you're away and train-less, make a deposit to the bank account in the amount of the storage quote you got in Step 1.
- At the end of 10 years, you will have ten times twelve times [the monthly storage payment], PLUS whatever you were able to get for selling your trains.
- At that time, look at the bank balance and decide whether you want to:
a) Buy replacement trains -- OR --
b) Add the money to whatever you had been saving for a house ... except now with the train money, you can afford a nicer house -- OR --
c) Send children to college, etc.
Those are my $0.02
SJS
P.S. During the entire 10-year period, refer to the sum in the bank account as "my train money". This will give you a 0.002% chance of achieving 6a. 
