Even rims that aren't tubeless ready can be converted by using tape on them, have done it in a previous bike, it is a bit of work since you have to take out the tire, tape the entire inside of the rim (which might be a couple of turns), and then you need to puncture the part of the rim with the hole for the valve and put a tubeless ready valve in there, the only disadvantage I noticed in relation to the ready made sort is that I did have to inflate the tires more often in a week because the air seal wasn't as good (but then again I had used a normalish tape for the conversation and not something proper).
Honestly if we exclude the work/cost of converting I see little reason to run with tubes, after making the change I haven't looked back, just make sure to put tire sealant (the slime being referenced here) inside the tire, and "refill" it once or twice a year if it goes dry, have had quite good results with stan's no tubes, only remember of 2 situations where I had to worry about flats while MTB, one was a rock that slashed a tire (the tire was unrecoverable there), and once where I had to stop because I had lost too much air from a puncture, by the time I stopped the puncture was fixed, but I had lost a bit of air so had to refill it with my hand pump.
That being said if you are getting flats due to punctures, there are tubes that are more resistant to flats, there are even tubes with sealant in them, although these last ones are probably not worth the cost given that the sealant can both dry out and run out, so unless it is refillable it shouldn't be worth it.
Oh yeah if you do use anything be it tubes or tubeless with sealant, do not use CO2 cartridges to inflate the tires, the low temperatures of the CO2 might crystallize the liquid making it pretty much useless.
