Let me explain you in laymen language to make you understand and confidence as well about both of these software.

In some case it can be but it depends on who is using this. Both are having their own capabilities. If client is big and they need premium support and huge data processing capabilities then SAS is good option and definitely you will use this. Same way if data is smaller or client is not ready to pay money then you will use R.

Lots of guys will answer that R is free and SAS is paid therefore R is alternative. But it is not like that. To learn both are free, to work both are free for you. If client want you to use SAS then they will pay the cost and your company will give you to work on SAS only with salary ;).

Same way if client is having smaller data to process then why they will buy SAS license when it can be done in R only. Same way if client is not having money then they will ask to your somehow work in R whether they have huge data. In that case you must have server access other wise you will not be able to work then your company will charge server price to your client because they want you to work on R on huge data.

Let me give you once example you want 100 guys to travel with you then will you take 1 car with capacity of 5 guys or you will look for caravan with capacity of 100 guys. Here if you want to travel whether you have money or not you will have to go for caravan only. This is example for SAS usage.

Now lets discuss if you do not have money to pay for caravan of 100 guys capacity then what you will do? You will look for some cheaper solution Then you may go for train option but there as well you will have to pay cost 100 guys. But 100 guys will not travel with peace which they were getting in their own caravan. same way if client is not ready to pay they will ask to work on R and you will work on R but you will have to have server access and client will have to pay for server because server does not come free, only R comes.

Same way if you have only 5 guys then you will not go for 100 guys capacity caravan. You will go for car with capacity of 5 guys only. You can correlate this example with R and SAS. Here 100 guys or 5 guys are data size. and Caravan and Car are SAS and R.

Same question can be asked for SAS vs Python because R is also free. for SAS and Python as same example will be applied. 

Now last thing comes what should you learn?

You must learn in combination of SAS + Python or SAS + R. let me tell you again with one example suppose You have company where sometimes you travel with 100 guys. sometimes with 50 and 10 and 5. Then which transport company you will contact.

Will you contact that company which is having one 100 guys capacity and if you need 50 guys capacity vehicle then you go to another transport company which is having vehicle of 50 capacity and so on. Obviously you will not go for this solution.

You will go for transport company which is having all types of vehicle. You make call and they send vehicle as per your requirement.

Same way companies hire employees for SAS + Python or SAS + R combination guys because based on client requirement they will ask you to work on required tool. No company would like to give salary to sit on bench. It is truth. Now you need to be open to learn multiple technology which will help you to get job easily. job will the secured as well.