Good question there. I'm an AA G for life (million miler); another 500K miles and I'm AA P for life. But no E+ there, so if I don't get upgraded, and don't get exit row seating, I'm back in the same boat as with AS. And I'd much rather fly AS than AA.
When I knew I was moving from RDU to SEA, and that I'd be traveling more than ever before, I took a long look at the situation and ended up saying to myself that I'd fly UA for transcons, making 1K easily, and AS for West Coast flights, probably being lucky to make MVP. But then I did more traveling than expected on AS, and did a lot on DL on the East Coast, and found myself unexpectedly making MVPG. So here I am with 1K (which, after DEQMs post, I've almost requalified for already) and thinking that I'd like to keep my MVPG status. Plus those transcons are convenient to DCA (closer to some of my meetings than IAD) and MCO (no stop in IAD or ORD, and no TED). So it has been tempting.
I feel for you, but it ain't going to happen. At the rate UA is going, they're knocking on bankruptcy's door again and I bet will be swallowed up this time and alas, E+ will fade away like AA's More Room in Coach.
It's funny: not one person here besides me has thought it would be a good idea for AS to introduce an E+ like feature. So if the elites don't like it, it's a reasonable bet that AS management doesn't think it's a good idea, either.
I think where I'll end up is a modified version of my original strategy:
1. For West Coast flights, AS. Upgrades are plentiful and they're short flights if not.
2. For transcons where AS has nonstops, trying making plans earlier. Check AS first to see if upgrades and/or exit rows are available. If so, book AS. If not, go UA.
I'm flying about 150-160K BIS miles/year these days, so if I play things just right, I could still end up with not only 1K but MVPG and no bad seats. But it all depends on my ability to plan trips farther in advance, which is difficult.