But I am worried about Trump's reaction.

Whats behind door number 3?!?

You have to believe that at this point, the questions they are asking are very focussed to evidence they already have. They likely know the answers, and are judging if the witnesses are either lying to them or trying to see if they have anything to add.

Just look at who is cooperating: flynn, bannon, hicks, gorka, giuliani, gates, mcgann, page... and that's just a partial list. You know they probably cracked lawyers, accountants, bankers, gangsters, and politicians.

Right now, they must be like a cat that injures a mouse, and then just watches it and occassionaly plays with it.

references CNN article in the OP

https://talkingpointsmemo.com/edblog/not-excellent-news-for-donald-trump

This from CNN could be nothing, just checking off boxes. But it sounds ominous for Donald Trump …

Investigators for special counsel Robert Mueller have recently been asking witnesses about Donald Trump’s business activities in Russia prior to the 2016 presidential campaign as he considered a run for president, according to three people familiar with the matter.

Questions to some witnesses during wide-ranging interviews included the timing of Trump’s decision to seek the presidency, potentially compromising information the Russians may have had about him, and why efforts to brand a Trump Tower in Moscow fell through, two sources said.

The article elaborates on these points – in questioning other witnesses, Mueller’s investigators are asking about when Donald Trump became serious about running for President, how this chronology overlapped with various business ventures, who paid for what on his 2013 visit to Russia and what access people had to the now-President to gain compromising information about the President.

Most of the article is not able to get past ‘the questions were asked’. But even in hints and clues you can see the storyline and chain of events beginning to draw tight.

He is SO STUPID! Why don't a whole collective of supposedly intelligent people not see that?

he was recruited to run, and promised the help of the kremlin from jumpstreet.

and it will happen when Mueller compels Trump to testify under oath.

Also think it will roil the stock market.

What's critical is everything that lead up to the 2013 Miss Universe pageant in Moscow, what actually happened at the Miss Universe Pageant, and the time period immediately after the Miss Universe pageant.

That's going to be some good, good stuff.