According to latest rumors, the Fujifilm X-T4 will replace currently X-T3 in late 2020. Here are first rumored specs of Fujifilm X-T4:
IBIS
Fujifilm X-T4 to be Announced in the Second Half of 2020
The Fujifilm X-T3 was officially announced in September, 2018. We just got from our trusted source that Fujifilm is planning to release the Fujifilm X-T4 in 2020, around the second half 2020.