Anything involving energies brought through the looping of time represent a state of flux and ongoing change. There is a kind of pulse that flows and it will vary with respect to the details of the energies assigned, as a function of changes in the other time domain looping to the present. So it is true that a future potential to have an outstanding healing session may affect the past but then be partly undone if there is not a true follow through at that future point in time because of an unforeseen event so it was not set in motion until a later point. This could come about for any number of reasons, including the practitioner not being alive due to a sudden accidental death prior to carrying out the intended work, but the benefits would still have taken place because energy is energy and anything conducted in a future extension is real, even though it is provisional, in a sense, because it is subject to potential change, but that is true of the present in all respects as well, the energies are in a state of flux coming to bear in the present moment, and so is indeterminate until the energy is utilized and turned into some productive consequence or action, as the case may be.
Once a future life extension has taken place to create a healing session, that healing energy will have an influence and will affect karma even if that actual future eventuality becomes somewhat different. So in a sense, there is not a single moment from the future that has an opportunity to loop back and forth, it is a continuum. So each and every moment of that future timeline will be looping and is a potential influencer of other time domains. This is difficult to understand because you think of time as being linear when all is in creation in the now, in a simultaneity of occurrences. This is why the influence of other perceived timelines can be so meaningful—they are existing in the moment and can have a significant consequence on what is happening in your reality.
So the question posed about a potential fade in the benefits would pertain to that portion of life being lived beyond that point in the future life extension. What would continue to loop would be an attenuated energy or an absence of energy if the session were prevented from taking place. What this speaks to is the need to do one’s best, always, and to strive to make continual growth enhancement and greater precision and accuracy in all one does so there is only a strengthening over time and not a lessening. Even when doing that in a general way, there will be times when things will vary from the average. People have limits in how smart they can get, how energetic, and, of course, the time constraints imposed by the clock which is a fundamental constraint of human existence. You cannot work 24 hours a day, there must be a period of rest to restore the workings of the body and maintain health, so all energies will have a tempo and a state of rise and fall energetically with respect to intensity, focus, and the assignment to particular karmic entanglements.