I don't know if it will be in HF26 or not, depends on too many future events to say. I don't expect to start planning for HF26 until HF25 code enters the testing phase (about a month before release of HF25).

As for the timing of HF26, the idea is to maintain a 6 month development cycle for hardforks when we can, so if we expect HF25 in June, we're likely talking December for HF26. But that's not a hard-and-fast rule, just a general guideline. HFs can be slower or faster depending on what's being done and the urgency of the issue.