It is not uncommon for nationally (and internationally) recognized con events to happen on the same weekend, but the final weekend of March 2019 seems to be the top pick for no less than three big conventions.
March 29th-31st 2019 just happens to be the chosen dates of C2E2 in Chicago, WonderCon in Anaheim, Planet Comicon in Kansas City, and apparently also Silicon Valley Comic Con in San Jose (who have yet to officially announce 2019 dates).
Looking at the FanCons.com website, if you scroll down into the 2019 dates, you can see that all four of the mentioned cons are at this time listed for the same weekend:
Next year will be Planet Comicon's 20th anniversary, an impressive milestone for any event to celebrate let alone a fandom-centric event in the current arguably oversaturated market.
We've reached out to representatives for SVCC to comment on the likelihood of their fourth event dates being that popular weekend too, but haven't heard back yet at the time of publication.
Again, multiple events on the same weekend aren't a new thing — but shows of this size rarely all converge on the same dates in this number. Obviously that's not counting prime three-day weekend events that happen over Memorial Day and Labor Day.
There is no telling how such a CONvergence might affect each event's guest lists, not to mention the numerous support staff who work at more than one of those shows.
We'll keep you updated as any additional information becomes available.