Are there any portfolio planning software tools that handle scenario planning for changing demand?

Yes — there are several portfolio planning / portfolio optimization tools that support scenario planning, including cases where demand changes over time. The best fit depends on whether you mean:

1. Product / project portfolio planning
2. Supply chain / inventory / demand planning
3. Capital allocation / financial portfolio planning

Tools that commonly support scenario planning for changing demand

Enterprise portfolio / planning platforms

• Planview
  Strong for portfolio, capacity, and roadmap planning; supports “what-if” scenarios and prioritization under changing demand assumptions.
• Anaplan
  Very strong for scenario modeling and demand-driven planning across finance, sales, and operations.
• Workday Adaptive Planning
  Good for financial and workforce planning with scenario analysis and rolling forecasts.
• Oracle Primavera / Oracle Cloud EPM
  Useful for project and enterprise planning with scenario and forecasting capabilities.
• SAP Analytics Cloud / SAP IBP
  Good for integrated business planning and demand/supply scenario analysis.

Product portfolio / R&D / innovation portfolio tools

• Planisware
  Commonly used for strategic portfolio planning and scenario analysis across changing assumptions.
• Sopheon Accolade
  Strong in innovation and product portfolio decision-making with scenario-based prioritization.
• Broadcom Clarity PPM
  Has portfolio analysis and what-if planning features.
• Microsoft Project / Power BI with planning models
  Not as specialized, but can be combined with custom models for scenario analysis.

Demand / supply planning tools with scenario capabilities

• Blue Yonder
• Kinaxis RapidResponse
• o9 Solutions
• ToolsGroup These are especially good if your “portfolio” is tied to products, inventory, or supply chain capacity and demand shifts are central.

What to look for

If changing demand is your main concern, look for tools that support:

• What-if scenarios
• Rolling forecasts
• Demand sensing / demand forecasting
• Capacity constraints
• Sensitivity analysis
• Multi-scenario comparison
• Versioning and assumption management

Quick recommendation

• For cross-functional enterprise scenario planning: Anaplan or Planview
• For product/innovation portfolios: Planisware or Sopheon
• For demand-driven supply planning: Kinaxis, o9, or Blue Yonder

If you want, I can also give you:

• a comparison table of the top tools,
• recommendations by company size/budget, or
• tools specifically suited to project portfolio planning with fluctuating demand.