$64 million question. What are the locos you have bought and are their DCC cards factory fitted or aftermarket products ? Another option may still be to operate them in DC mode until you decide how you want to develop your line. I have a late model Bachmann 1:20.3 scale Spectrum Climax with a factory fitted DCC/sound card, yet it will happily run on DC, even with its chuff and idle sounds functioning. You will only have a limited number of features that will still operate, possibly only speed control. I can do the same with my DCC/sound fitted 009 1:76 scale double Fairley, and again it still chuffs.
As Gavin says you can usually take out the DCC card and just run DC, although, as mentioned you may need to get a knowledgable person rewire the loco if you do not have the skills...or just ask on this forum ! I bought an LGB track cleaner loco a number of years ago fitted with their MTS DCC system (didn't check before buying). I run(ran) DC at the time (Crest Train Engineer, now augmented by battery/DCC/RC and live steam) it ran fine with the card removed and loco rewired. I retained the card so the loco could be sold on with it, why cut your market potential
Max
P.S. You can pretty much migrate backwards and forwards through most of the operational methods outlined with most electric motor driven locos - track power DC or DCC, on board battery power with or without RC, DC or DCC. In some cases a maker produces both electric and a live steam versions of the same loco using most of the same tooling, but they are not really practical to switch power methods
. With some these mode of operation changes are made easy, some not so. That is what I have been doing.