The Fujifilm X-H2 has rumored for a long time. Since Fujifilm X-T4 will be officially announced soon, so next high-end X-mount mirrorless camera will probably be Fujifilm X-H2. But Fujifilm X-H2 will not coming soon until in 2021.
Nokishita Camera has just leaked the size and weight of upcoming Fujifilm X-T4 x-mount mirrorless camera. The size for Fujifilm X-T4 is 134.6 x 92.8 x 63.8 mm, and the weight for X-T4 is 607g. For comparison, X-T4 size is 132.5 x 92.8 x 58.8 mm, weight is 539g.