Policies are cyclical in nature. In the United States, immigration would eventually be reformed by prioritizing skilled labor over lucky labor. When and how it will be done is entirely uncertain.
An economy like US can't afford to continue on an incompetent immigration system forever.
Another school of thought is that developed countries need immigration only during good times when unemployment rates are low and economy is booming. Presently, as predicted by various CEOs, we are heading for a mild recession and understandably, this is probably not the right time for USA to prioritize immigration at the top of its To-do list.
Trump is actually doing the right thing for his country. There aren't those many jobs there to support huge influx of immigrants. In my company, the kind of work done by my Indian team (only B.Techs) is same as the work done by Ph.Ds there in US. This exemplifies the bar there to fill in limited positions from a candidate pool with advanced degrees from Ivy Leagues.
To summarize, we should not have high hopes from USA at least in the next 10 years.
I think you are right that immigration policy changes over time. In my opinion, one main factor affecting a country's immigration policy is the demand for additional labour for its various sectors. With this in mind, as long as the country's economy is performing well, and to ensure it continues to do so, it will require more skilled immigration. With the American economy doing well, it is still a viable option for many in particular those that have a relative less chance of getting ITA soon.
One thing about the skill levels in the US labour market.... There is still a huge gap to in the middle category such as B.Techs and this lead to positions filled by over qualified staff. This might be one reason making it difficult for US firms to be competitive in many areas. This fact might require to relax the immigration rules to some extent so that to get the required pool of experts.
On the other hand, the current inward looking policy of Tramp is clearly anti immigration and this has only helped other countries when it comes to attracting the competitive talent the economy requires. I am sure this is not something hidden from the US policy makers and once this policy changes (either after Tramp or while he is in power) the possibility of skilled immigration to the US will significantly change for good. That way, the US industries may return their competitiveness and stop the trade wars they have started with everyone and focus on fixing their side of the function.
In general, there are many factors that can change a policy of a country and sometimes such policy changes will affect the situation in other countries too. I assume we will see some of these changes soon.