One may always be able to get Calcium Hydroxide, unless they close down the building industry !
For it is used in cement and construction, and you could just buy a 50# bag of the construction Calcium Hydroxide and put it into a stove and heat it to a high temp to sterilize it and it may then be safe for Food use !
And "IF" you are worried about it being unavailable to you, then just buy 1 or 2 pounds and it may Last you the Rest of your Life !
As to how long one should take the Alkalizing Drink, I guess this depends on how long you want to stay healthy !
This question is about like saying you should "STOP" eating any food, because you may come to enjoy eating and want to eat each day !
Smile Tis your choice.