Yeah No such amendment still come.
And as per Rule 4(2)(a) of CENVAT CREDIT RULES,2004 it is clearly written that u can avail credit Not exceeding 50%. that means u can avail credit upto 50%. There is no such mandatory that we have to claim credit exectly 50%. even we can claim credit less than 50% and accordingly as per clause (b) of the said sub-rule balancing credit can avail in any subsequent year.
Here we have to nate that the word use is 'balancing credit' not the word 50% balancing credit. So if we have claim only 10% credit in first year than remaing 90% credit we can claim in any subsequent year.
And second things we have to note down that here word use is 'any subsequent year' i.e it is not necessary that the balancing credit we have claim in next subsequent year. the word use is 'any subsequent year'