I don’t get it why would somebody go for Yallo if they can have Salt for the same price.
I’m pretty sure they will renew it at the same condiitons. Even if they didn’t, I’m sure they will offer the same deal many times within these two years, so you can just renew it before the 2 years run out. Just think about it: they know that you are a customer who will not pay more than 29, so if they hit you with a double price, you will go away. They charge suckers with 59, and the ones who don’t want to pay that much can get a reduction.
I can even tell you that I called Salt and they offered the 29 CHF deal to my girlfriend, even though officially there was no promotion at that time. (it was like 1 week later)
It’s common practice in marketing to try to sell to the customer at the maximum price he is willing to pay. So the official price is high, but if you look for ways to get it cheaper, you will find them.