Question

帮我分析一下语法结构，详细些，谢谢。

4. What naturally happens is you end up with one company dominating the field, so through history there is no alternative to really coming in and breaking things up," he told Reuters.

Answer 1

他告诉路透社：“如果任其发展下去，最终将会出现某一公司在某一领域一家独大的局面，而纵观历史，没有替代者能真正涌现出来从而打破行业格局。”
（What naturally happens is you end up with one company dominating the field, so through history there is no alternative to really coming in and breaking things up," ）he主语 told谓语 Reuters宾语. 直接英语是宾语从句
What naturally happens is you end up with one company dominating the field, so through history there is no alternative to really coming in and breaking things up,

Answer 2

这是一个复杂句。我想你只需要直接引语部分的语法分析。
这是由so连接两个独立分句的并列句。
先看so之前的独立分句：
what naturally happens是名词从句做分句的主语，该名词从句中what是主语，happens是谓语，naturally是副词做状语修饰happens; is分句的谓语，is之后省略了表语从句引导词that, you end....field是表语从句。
表语从句中you 是主语，end up是谓语,with ....field是独立结构做方式状语，说明end up的方式；
方式状语中one company是dominating的逻辑主语，dominating the field是现在分词短语做company的后置定语，其中the field是dominating的宾语。
再看so后面的独立分句：
through history是时间状语，后接there be存现结构，alternatives是主语, to是介词引导后面的两个并列的动名词短语，做alternatives的后置定语。really是副词做状语修饰coming in.
希望我的解释为你解开了疑惑。有点复杂，得仔细阅读。