CCP have proposed changes to the use of racial isotopes for jump/jump bridge capable ships.
It hasn't been said, at least in the three pages of responses I read on the Forums, but this does appear to be a partial nerf (despite CCP Fozzie saying that "[we] don't expect this change to significantly impact behaviour around jump drive power projection") directed at capital ship proliferation as well as an attempt to 'balance the books' with the excepted drop in tower usage in high sec once the new industry changes come in to effect.
What Is Changing
Initially fuel bays were going to be increased by 50% (60% for black ops) but after a comment suggesting a one third reduction in isotope size that has changed to leaving fuel bays as-is but reducing the size of isotopes by one third or from 0.15m3 to 0.10m3.
This will mean more fuel can be carried (by one third) but the 50% increase in fuel usage will lower their range due to the consumption but also the amount carried meaning that crossing the galaxy in minutes is going to be slower and cost more. The only example given was a high sec to null sec Rhea run that showed a 50% increase in fuel costs and this did not show a breakdown of what the trip was or how much fuel was consumed (so i'd say its a poor example).
What Does This Mean To Me
I see costs increasing (not a surprise, the industry changes were going to do that anyway but this adds extra overhead) and I think I'm going to have to stockpile isotopes before the Summer Expansion in my jump locations so I can ensure I'll have a steady supply at least for 2/3 months afterwards.
I'm also considering changing my jump freighter fleet from Ark's to Nomad's to take advantage of the isotopes available in the region I'm in. A couple of hours mining a week should cover my fuel costs but I will need to look into this in more detail.