Different companies can make different decisions on this. For example, a company could want everyone to be in the office at the same time (for cooperative purposes), while another company may prefer people to be present at different times (so they can lease a smaller office space).
I've already heard about both approaches being used/planned by different companies.
It's impossible to say what your company's specific expectation of office presence will be.
So, for workers who telecommute full time or a couple of days a week, is there justification for them to maintain the 4/40 or 9/80 work schedules?
I don't see how the new system would preclude those options.
- Fulltime teleworkers were already not necessary to be at the office. You didn't provide a reason (or possibility) why that would now become necessary
- If the company defines specific days/times for people to be present at the office, then 4/40 and 9/80 workers can still be present for those times. Since these workers work more than the standard 8 hours a day, therefore they are inherently able to be present for an 8 hour work day (and presumably come in earlier or stay longer to cover for the extra hours).
This is just my interpretation. In the end, the decision is up to your company. But I don't see any blocking issues here.
Are there studies that in and of itself the alternate schedule might increase productivity?
Anecdotally, many (but not all) developers I work with say that they're more productive at home than in the office.
While you could cynically argue that this is just a false claim they make as a way for them to get permission to work from home, observing the backlog does support this claim for most developers - work is predominantly being done at the same rate or faster.
Or are there other benefits to the organization that aren't traffic or environmentally related?
As mentioned before, the ability to downsize the office space can be a great way for a company to save on expenses - but this can cut down on coordination since not everyone can be in the office at the same time. Whether this is a problem or not is situational and can't be answered universally.