I think it's just to early to say.
The car isn't available yet in the US. The reviews thus far have been from (1) brief drives, (2) manufacturer-managed events, (3) enthusiastic early purchasers, or (4) YouTube testers who have gotten access to the car through the good graces of a dealership and aren't likely to jeopardize that relationship by either over-taxing the car or giving it a terrible review. But what information we have so far is certainly positive. I don't anticipate that full-blown road tests by automotive journalists will contradict early impressions, but we just don't know.
The main factor driving resale value will be demand. We just can't say now what demand will be for these a few years down the road. New cars tend to generate demand. As time passes, the demand can either decline, remain the same, or increase. If Genesis gets established as a premium brand, that bodes well. If the release of SUVs/CUVs from Genesis saps all of the demand away from sedans (to consider one possible scenario), that won't bode well.
And, of course, the whole dealership thing in the US needs to get sorted out to everyone's satisfaction.
I see no reason why resale value wouldn't be at least decent, unless some unanticipated and thus far unidentified problems pop up.
But such things can and do occur. Consider a few examples (I'm sure there are lots more out there):
(1) According to a Car and Driver article from a few years ago, new models had 14% more initial quality problems than models that were returning unchanged from the previous model year or merely updated. So, as time passes, later models may be perceived as better than the originals.
(2) In 1978, I bought a Volkswagen Scirocco based on the Golf platform. The car had gotten rave reviews and was an Editor's Pick by Consumer Reports. Within a year, a whole bunch of unforeseen problems cropped up, including catastrophic drive belt failures that could drop valves into the oncoming path of the pistons and destroy the engine. Although I avoided the engine's complete demise, I did have the belt failure, along with a whole bunch of other issues that plagued that car. Consumer Reports issued damning criticism of the car -- way too late for a lot of people -- and warned against purchasing it used. Nobody saw that one coming in advance. I've not trusted Consumer Reports since.
(3) Tesla has recalled 123,000 Model S cars (the pricey sedans) for a corrosion-related power steering belt issue. It's eminently fixable but was certainly unexpected. Stuff like this just goes wrong sometimes. Tesla seems to survive all sorts of missteps but Genesis may not be so lucky if problems arise.
(4) Ford will be discontinuing a bunch of models in the near future, which could impact sales of those models adversely. What if, after the SUV's come out, the G70 gets axed? Will they go up in value? Down? Stay the same? For many, a perceived lack of enthusiasm for a model from the manufacturer will dampen their desire to get that model, especially if they're uncertain (as most people would likely be) about why it was discontinued. Now, we don't foresee the discontinuation of the G70 as in any sense planned in the near future, of course. But we really don't know what will happen, do we? We're not even confident when the car will appear in dealerships, even though the company is committed to a US release.
It's always a bit of a gamble with a new model from, essentially, a new car company. That's why pricing is often (wisely) aggressive when such cars are first released. Once they've proven themselves those cars can command higher prices. But initially, they carry some uncertainty, which essentially diminishes their value somewhat until they prove themselves. Again, I don't see any signs that problems that could occur will occur in the case of the G70. Early signs point to it being a solid car and people who see and drive it generally like it. But early adopters always take something of a risk. Sometimes that works out well and sometimes not.
