I'd expect a model designed to bring the price down, but that might not mean any drastic changes - I don't think Nintendo will want to splinter the market and remove the modular nature of the Switch by, for example, releasing a 'handheld only' version. Manufacturing yields and nips and tucks in design could easily help them bring the shelf price down a little without making any radical changes to the device.
What interests me is that WSJ report that the hardware refresh is coming about because Nintendo are concerned about Switch's sales momentum. While a redesign was inevitable at some point, 2019 feels slightly too early to me - I thought 2020 was a lock, especially given major sellers like Mario Bros, Animal Crossing and Pokemon are already scheduled for 2019, and we've yet to see what Super Mario Party, Pokemon Let's Go and Smash Ultimate do for hardware sales. I think we'll have a much better indication of whether or not a redesign is coming by the end of the month, when Nintendo release Q2 numbers. If Switch shipments are down or flat on last year, then it's entirely possible Nintendo are concerned the system is losing momentum.
However, that would just show Nintendo are still all over the place in their thinking - Switch hasn't had a major system selling release for 12 months now. Are Nintendo seriously surprised they lost some momentum by leaning on ports, experimental software and middle-tier games for a year? Are they really going to schedule a hardware redesign without waiting to see how the next six months go? Switch could generate a huge amount of momentum over the next few months, especially if Mario Party and Bros sell strongly alongside Pokemon and Smash. Maybe this redesign is part of the plan to get multiple Switch systems in each household, but if it's a reaction to slowing sales, then I'd be a bit concerned, because it suggests Nintendo still don't understand that they need to release their major titles consistently and evenly throughout the year to maintain a strong baseline.
Let's see what happens at the Q2 results, anyway.