I'm saving my money to buy a new 225-A1 and M11-A1. My question is, how likely is it that Sig would discontinue one of these models in the next couple of years? If they do, then I would want to buy that model first.

I understand the way you feel.
I have the p239 that is discontinued and now wonder about parts be be around like springs.

The 225 is a little bigger than the p239 so not in a rush to change over.
I liked the P239 model for size. Not to big and not to small.

With Sig, who knows...

Since they are discontinuing the 239, I'd think the new 225 would be around for a while.

The M11... or some version of it (229) should still be available.

With sig you never know. its just a CNC machine. But with the 239 gone I think the 225 will go shortly.
The 229 based stuff will be long lasting.

I wouldn't think they would discontue the P225 A-1, it too nice a gun, it's right there with my Legions for quality and reliability, as a single stack it's an awesome gun, and totally accurate, I don't know for sure, but I think the re-do of the P225 will be around for some time, and worth having if you're a Sig guy..