I think I read somewhere they've taken a thousand criminals off the streets so far. If the NG left today, that means there's a thousand less criminal roaming around DC.
Do you think there's another thousand people waiting to take their place as soon as the NG leaves?
Yes. Among other things...
First, violent crime decreased not because of arrests, but because of NG presence. So, once the NG leaves, the violent crime will go back up as it doesn't seem (according to various reports from various agencies) that many arrested were arrested for violent crimes. Not saying there weren't arrests of violent criminals (or criminals with a violent past), but most likely they were not violent offenders.
Gang violence and gang-related crimes as well as drug-related crimes are what are problems in cities (red or blue). There has not been reports of gangs being mass arrested or in numbers that would diminish them. Theya re just laying low because they know that they can go back to business as usual once the NG leaves
Also, most of the NG appear NOT to have been deployed in mostly at-risk neighborhoods like in SE & SW. A few patrols certainly, but they have been deployed in mostly NW & NE where it is more touristy and white and not that affected by violent crime or drug crime. Again, the exaggeration of the administration over the crime of DC is notable. If they were really serious, the NG would be assisting in force in SE & SW. Which leads to the next point...
They can't arrest anyone. By law. They can detain until local authorities arrive or do crowd control, but that's really it. And now they are in NW & NE doing beautification missions. So, while their presence has had an effect, the real effect is only that assisted in areas that are not that really victimized by violent and/or drug crimes.
It should also be noted that courts are throwing out cases with misdemeanors and there is a growing movement of grand juries not indicting. This is in part of arresting so many over offenses that are small and meaningless (for the most part) the courts are now overwhelmed...so a lot of these folks are just having their cases dismissed and allowed back on the street. As usual, the Trump administration did not think to bolster the actual court system prior to doing this. In other words...this was doomed to fail before it even started.
Side Note - I deal with distributors out of DC on a daily basis, I was born in DC, grew up in the Metro area and worked for years in DC (including the Smithsonian) before moving to Baltimore: crime is always a worry in any city, and it is always good to be aware when you move about in one...but this nonsense was not warranted. And once the NG units leaves, you will see how badly this plan failed in its mission...but succeeded in the REAL mission of duping those who don't know any better to get optics from the base.
But hey...what else should anyone expect from Dear Leader Trump and his MAGA Socialist Party?