For:

正方辩词：

The extreme sports will be the mainstream sport.
极限运动将成为未来体运动的主流。

At present, more and more modern people are tired of the monotonous life. They desire to experience something interesting and exciting. The desire to experience something interesting and exciting. The extreme sports such as bungee jumping, sky diving and ice climbing meet their needs. So I think the extreme sports will be the mainstream sport in the future.
如今，越来越多的现代人厌倦了单调的生活，他们渴望经历一些有趣剌激的事情。如蹦极、空中跳水、攀冰等极限运动都正和他们胃口。因此，极限运动将会成为未来的主流运动。
Besides, the extreme sports are beneficial to explore and develop our potentials when we are facing challenges and difficulties. Therefore, more and more people will love these sports activities and promote the extreme sports to the top position in the future.
另外，极限运动中会面对很多挑战与困难，这将对开发及发展我们的潜能有很大帮助。因此，越来越多的人喜欢上了极限运动，从而在未来极限运动将会被推向顶峰。

Against:

反方辩词：

The extreme sports woo't be the mainstream sport.
极限运动不会成为主流体育运动。

Although the extreme sports are paid more and more attention by us, these activities are designed for a certain group of people rather than the general public, since these sports are related to high risks and dangers.
尽管极限运动越来越被大家所关注，但是，由于这些运动常常伴随着高风险和高危险性，因此它们仅仅是为某一特定人群而设计的，并不能成为全民普及运动。
As we know, the extreme sports need professional skills and gears. Most people are not qualified to do these activities. In this sense, the extreme sports are not for everyone, so the extreme sports won't be the mainstream sport in the future.
我们知道，极限运动需要专业的技术和装备，而大部分人并不具备参加极限运动的资格。因此，极限运动并不适合每一个人，而它也不会成为未来体育运动的主流。