@punkin - I'm going to say a bit about life time language and Amex.
Amex is always going to do what's best for Amex. They've had lifetime language as far as I can remember. I've been a card holder since the 90ties (after I divorced using my own developing earnings ie nothing big).
I've had up to 7 Amex credit cards well before I had a charge card from them. I took myself down to 4 credit cards and recently got the Surpass which I had gotten the pop up for not too long before. Many people got the pop up by applying with various links. I didn't see anybody report getting it from Doc's link.
Most of the shut downs are usually very heavy hitters. People who do 3-4 cards in a year are not heavy hitters.
Chase could have followed the Amex lead long ago. I'm sure they understand the business. I highly doubt they will go further than the one every 2 years with many branded cards and the every four years with their premium products. With branded cards, the brand has input. We've seen that with Marriott. Marriott makes their own rules as part of their agreements with both issuers.
With their own business cards Chase rolls the dice. They do good promos because it's a crapshoot of who will be the next 'big' deal. Right now they've gone with high SUB's and almost moderate rewards. I don't think we are going to see a whole lot of changes anytime soon. They'll stay with what pays the bills. Not everyone out there is a churner.
When we apply, they can always say 'No'. And later on they usually say 'Yes' in time and with some moderation.
I do think the most important thing past moderating app's is to make consistent payments, with nothing late, and keep rollovers to a minimum (moving debt to no interest card offers).