There still don't seem to be any plan changes. At this point, Fi is pretty expensive compared to competitors. Fi only makes sense if you are an incredibly light data user, you are one of the few people who both live in one of the specific areas in which network switching helps and have one of the handful of phones that can take advantage of it (the iPhone is not on that list), or you are a frequent international traveler. No one falls into that last category at the moment, but this eSIM support would potentially make that a slightly more favorable option for a future iPhone user who travels, but I doubt it attracts many new customers.
It is worth noting that even with this upgrade, Google FI is still just a T-Mobile MVNO (mobile virtual network operator) on the iPhone. The Verizon, Spring and US Cellular networks are not supported on the iPhone.
For the people complaining about Fi being more expensive for the same features: Google Fi is also the only US carrier that protects your line from porting and SIM swaps with actual two-factor authentication. I’m willing to pay for security.