As follows (not as follow ) is the established form of the idiom,no matter whether the noun that precedes it is singular or plural:
As follows （不是 as follow ）是惯用语的构成形式,而不管前面的名词是单数还是复数形式：
The regulations are as follows.
规则如下所述.
as follows只是一种固定搭配,所以可以不符合语法.像这类固定搭配都是约定俗称的,根本没办法从语法角度去分析,比如还有一句“long time no see”是“好久不见”的意思,这也是一种固定句式,不需要用语法去分析.
总之,as follows就是一种固定说法,本身的词性不需要具体分析.具体在句子当中做的成分应该理解成表语,因为“主语+be动词+表语”是一种基本句子结构.