As of February this year, the entry level Nikon D3300 has been a discontinued camera in Japan. If you log onto B&H and make a quick search the Nikon D5300 will not be found. That can mean only one thing and that is a new Nikon entry level camera is due. That camera could be very well be the Nikon D3400 or the D3500.
Ever since the D3300 went discontinued, the rumor mills have been abuzz about the possible successor. It is highly likely that the new camera will have a 24 megapixel sensor. Native 4K video will likely not be available on the new camera. Going by the trend the new camera is likely going to have SnapBridge compatibility as well.
There was a thought circulating that the D3xxx series will be remodeled into a prosumer mirrorless camera offering. That rumor may just turn out to be baseless after all.