Well... that's certainly a viable option if you're going to be happy using the older hardware... especially if you can get a good deal on them.

I can't speak to what Apple are considering doing with the support of the older Intel-based systems now that they are making their own silicon... but they have usually been "pretty good" with that sort of thing. I mean, when they did the last silicon swap (PowerPC -> Intel), the support was ongoing for something like 7 years!

Additionally, the transition is scheduled to take place over 2 years or so... so it really shouldn't be an issue in the near term.