It is highly possible that JAXA will decide to create in the cooperation with NASA replacement for lost Hitomi (Astro-H) satellite.
According to Twitter profile of Naoki Okumura, President of JAXA, Agency already requested for additional funds for Astro-H2, replacement of Astro-H, in next, 2017 fiscal year (in Japan fiscal year lasts from 1 April to 31 March) and obtain full agreement from Japan’s Finance Ministry. If extended budget for JAXA would be accepted by Diet (Kokkai is Japanese parliament), JAXA with help from NASA could finish Astro-H2 and launch it in 2020 or 2021 maybe on atop of new launch vehicle, HIII rocket (63 m long, with 6500 kg payload for GTO orbit with first launch scheduled for 2020/2021). But now everything is depending on agreement for extended budget with additional funds for Astro-H2 included.
It seemed that after appearance anomaly on JAXA X-ray satellite Hitomi on March 26, 2016 and following problems, which resulted in losing control over spacecraft combined with its final disintegration, JAXA will have problems with next such ambitious and complicated mission. Loss of Astro-H as a result of mistake in procedures implemented into onboard control systems combined with lack of appropriate control in ground segment of the mission, were huge pain for JAXA also in terms of Public Relations. Of course it is easy to imagine that even bigger problem was huge financial loss due the high cost of the mission, with estimated cost of the satellite at around $360 million.
However, even after anomaly with Hitomi, mission brought some interesting discovery announced by NASA. Goddard Space Flight Center in Greenbelt, Maryland, confirmed on July 2016, that before final loss of the Astro-H, satellite gathered important data using its Soft X-ray Spectrometer (SXS-designed and manufactured in Goddard SFC) on Perseus galaxy cluster. Information about success surely pushed NASA to look on Astro-H2 more positively. On July 20, 2016, it was given to public, that JAXA officially requested NASA for creating copy of SXS spectrometer to use it in next Astro-H satellite. JAXA declared that Astro-H2 could be even ready in 2020. NASA has not rejected request and confirmed that financial participation of Agency would remain under $90 million for manufacturing new spectrometer. It was definitely good sign for JAXA – but even if they would like to create Astro-H2 with free SXS device sponsored by NASA, still mission would require around $270 million to succeed (probably rest of the international partners would not be so generous as NASA). Increased cost will be probably covered by Japanese budget and this requires agreement from parliament. Hopefully Japanese authorities are still highly interested in developing own space industry, so it is quite sure that additional funds for Astro-H2 will be granted.