The following is all my own guesswork and in no way reflects anything official.
There is such a thing as a product life cycle. RO has had a fairly extended though rather shallow curve as its product life cycle profile. This relative longevity (in relation to initial marketing outlay) has mostly been due to a great deal of attention given to the community by the team rather than the usual "f*ck them then forget them" approach adopted by more 'professional' companies.
RO does, however, have to compete, with games that make more use of newer technologies and RO has always been a rather 'nichey' product anyway. Comes a point that no amount of warm fuzzies from and to the community are going to make an impact against the overall trend to next-gen (read 'now-gen') graphics etc. etc. that are competing for Joe Gamer's bucks.
Whether they specifically modelled that into their plans or not, Alan, John et al. must have been aware of this coming anyway. Therefore an intelligent but uninformed guess is that, like a duck swimming, there is a hell of a lot of activity going on beneath the surface on getting the next game in place. Money needs to be made - Alan's plastic surgery and John's rifle rack for his Ferrari will not pay for themselves.
In the meantime TW probably decided it was time to capitalise on the goodwill generated in the community by encouraging mods as a kind of 'retirement plan' for RO. This pension scheme will gradually come into fruition in the coming months (don't quote me on when).
It's all perfectly natural and all thoroughly reasonable.
No need for 'ZOMG RO is dying' dramatics - it is over the 'hump' of its product life cycle for sure but, so is the VW Beetle, and that is one of my favourite cars.