This notion of "wasted" TPs is, imo, flawed. The point of achieving status is that you can use the perks of your status once achieved. If you are going to switch to another airline/alliance as soon as you achieve that status on the basis that the points afterwards are then "wasted", then what was the point of acquiring status in the first place?

Let us face it: if you earn enough for Silver but are not going to get anywhere near Gold in a year, you are probably not going to reach top status anywhere. What you want is a programme with a reasonable/good mid-tier level. IMO, BAEC fits the bill reasonably well and, if I were in your shoes, I would simply enjoy my silver status rather than torturing myself in trying to see whether I could grapple some minimal additional status elsewhere.