After the bad news regarding tariffs, I doubt that there will be a new camera announced in April.
I think they will wait and discus internally, whether that camera (no matter what it is) makes sense at all at the moment with these trade wars and if yes, at which price.
I don't know if you overdoing the influence of the tariffs.
America as a hole accounts for about 25 % of all camera sales, so USA alone will be a little less. Europe and China alone are about the same as America as a hole. And the market share of US sales is declining anyhow, compared to rising China sales and also India getting more important.
Also every market is different and not every brand is equally successful in every market. Canon for example is very strong in America. About one third of Canon's camera sales accounting for America, compared to about one quarter of overall camera sales accounting for America.
So it depends how important the US are for Panasonic compared to the rest of the world. As far I know the most important markets for Panasonic cameras are Europe and China, where they perform over proportional.
Also not every sale in the US will be lost because of the tariffs.
But in the short run, I think announcements and releases could be delayed, because the manufacturers have to do the pricing right and as far I know many US importers have problems calculating the tariffs correctly. At the moment there is many uncertainty about it. But I don't think any plans new camera or lens will be cancelled because of the tariffs. In the long run, I could imagine that some manufacturer will make downgraded versions for the US to be able to offer lower prices or priorities other markets.
The hole topic "Trump tariffs" is a little complicated and the impact varies depending on branches and brands. Possible for some manufacturer it could make sense to shift the production or a part of it to the US for some it could be the complete opposite and the tariffs could be a reason to shift production from the US to another country. Some European car manufacturers, like BMW, already have production facilities in the US and they can adopt well. Others like Jaguar can't and they already stopped US exports.
As for cameras, a shift of production to the US seems very unrealistic and maybe would increase prices for other markets that are maybe more important in the long term. To much of the value chain is in Asia and the tradition and knowledge is gone with Kodak.