Still going strong, probably more popular than ever. There is now 2 distinct ways to play the game online Magic Arena, and MTGO (Magic The Gathering Online). Full rules enforcement, matchmaking, drafting, etc. etc.

"Paper" Magic is still very popular, with a big 1000+ tournament happening throughout the US (and the world) every weekend.

The cost has unfortunately gone up, its pretty rare to find a $5 entry fee anymore. A pack of cards is $3.99 (or $9.99 for special sets). A competitive deck of cards can run $150-350 for the "Standard" format (only cards from the past 1-2 years) or $700-1500+ for "Modern" (most every card from 2003 onward).