Maybe the likes of Kelty Hearts who are already in League 2 - Bonnyrigg Rose in the Lowland League at a push - could make it to the Championship within ten years but the Premiership would be a step too far for them I think.
Teams of that size simply don’t have the fanbase to support teams in the top division.
The Premiership is really made of up 5 teams who are near or near about guaranteed to be in that division every year (Rangers, Celtic, Hearts, Hibs, Aberdeen) and the rest either yo-yo between the Prem/Championship (Ross County/Inverness) or go in cycles of staying up (Hamilton’s 5/6 year stay).
The bigger non-league sides will be slow to move up the pyramid because of the prohibitive set up of the League 2 Relegation Play-off. Currently the winners of the Highland/Lowland leagues play each other to determine who plays the 10th placed League 2 team in a 2 leg play off. Until automatic relegation places are in place then the pyramid will continue to bottleneck at the top of Tier 5.
But theoretically, I’d say the likeliest teams to be in the SPFL within 10 years would be Bonnyrigg (T5), Fraserburgh (T5) and Talbot (T6). I’ve not even began to consider the ambitious, well backed teams like Tranent and Linlithgow Rose (both T6) in the East.