  Transiting planets at young ages are key targets for improving our
understanding of the evolution of exo-atmospheres. We present results of a new
X-ray observation of V1298 Tau with XMM-Newton, aimed to determine more
accurately the high-energy irradiation of the four planets orbiting this
pre-main-sequence star, and the possible variability due to magnetic activity
on short and long time scales. Following the first measurements of planetary
masses in the V1298 Tau system, we revise early guesses of the current escape
rates from the planetary atmospheres, employing our updated atmospheric
evaporation models to predict the future evolution of the system. Contrary to
previous expectations, we find that the two outer Jupiter-size planets will not
be affected by any evaporation on Gyr time scales, and the same occurs for the
two smaller inner planets, unless their true masses are lower than $\sim 40$
M$_\oplus$. These results confirm that relatively massive planets can reach
their final position in the mass-radius diagram very early in their
evolutionary history.
